diff --git a/res/values/strings.xml b/res/values/strings.xml
index d0ad58a0d80..51a581fb490 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -502,6 +502,9 @@
     <!-- The content of a confirmation dialog indicating the impact when the user change the system region. [CHAR LIMIT=NONE]-->
     <string name="desc_notice_device_region_change">Your device will keep %s as a system language</string>
 
+    <!-- The content of a confirmation dialog indicating the impact when the user change the region of the preferred languages. [CHAR LIMIT=NONE]-->
+    <string name="desc_notice_device_region_change_for_preferred_language">%1$s will replace %2$s in your preferred languages</string>
+
     <!-- Title for asking to change system locale or not. [CHAR LIMIT=50]-->
     <string name="title_change_system_locale">Change system language to %s ?</string>
 
diff --git a/src/com/android/settings/localepicker/LocalePickerWithRegionActivity.java b/src/com/android/settings/localepicker/LocalePickerWithRegionActivity.java
index 6069c43fd16..9f67251e6bb 100644
--- a/src/com/android/settings/localepicker/LocalePickerWithRegionActivity.java
+++ b/src/com/android/settings/localepicker/LocalePickerWithRegionActivity.java
@@ -28,6 +28,7 @@ import android.view.MenuItem;
 import android.window.OnBackInvokedCallback;
 
 import androidx.core.view.ViewCompat;
+import androidx.fragment.app.FragmentManager;
 
 import com.android.internal.app.LocalePickerWithRegion;
 import com.android.internal.app.LocaleStore;
@@ -49,10 +50,15 @@ public class LocalePickerWithRegionActivity extends SettingsBaseActivity
     private static final String TAG = LocalePickerWithRegionActivity.class.getSimpleName();
     private static final String PARENT_FRAGMENT_NAME = "localeListEditor";
     private static final String CHILD_FRAGMENT_NAME = "LocalePickerWithRegion";
-    private static final int DIALOG_CHANGE_LOCALE_REGION = 1;
+    private static final int DIALOG_CHANGE_SYSTEM_LOCALE_REGION = 1;
+    private static final int DIALOG_CHANGE_PREFERRED_LOCALE_REGION = 2;
     private static final String ARG_DIALOG_TYPE = "arg_dialog_type";
     private static final String ARG_TARGET_LOCALE = "arg_target_locale";
+    private static final String ARG_REPLACED_TARGET_LOCALE = "arg_replaced_target_locale";
     private static final String TAG_DIALOG_CHANGE_REGION = "dialog_change_region";
+    private static final int DISPOSE = -1;
+    private static final int SHOW_DIALOG_FOR_SYSTEM_LANGUAGE = 0;
+    private static final int SHOW_DIALOG_FOR_PREFERRED_LANGUAGE = 1;
 
     private LocalePickerWithRegion mSelector;
 
@@ -111,21 +117,67 @@ public class LocalePickerWithRegionActivity extends SettingsBaseActivity
     @Override
     public void onLocaleSelected(LocaleStore.LocaleInfo locale) {
         if (Flags.regionalPreferencesApiEnabled()) {
-            if (sameLanguageAndScript(locale.getLocale(), LocaleList.getDefault().get(0))) {
-                Bundle args = new Bundle();
-                args.putInt(ARG_DIALOG_TYPE, DIALOG_CHANGE_LOCALE_REGION);
-                args.putSerializable(ARG_TARGET_LOCALE, locale);
-                RegionDialogFragment regionDialogFragment = RegionDialogFragment.newInstance();
-                regionDialogFragment.setArguments(args);
-                regionDialogFragment.show(getSupportFragmentManager(), TAG_DIALOG_CHANGE_REGION);
-            } else {
-                dispose(locale);
+            int index = indexOfSameLanguageAndScript(locale.getLocale());
+            switch(getDialogEvent(index)) {
+                case SHOW_DIALOG_FOR_SYSTEM_LANGUAGE:
+                    showDialogForSystemLanguage(locale, getSupportFragmentManager());
+                    break;
+                case SHOW_DIALOG_FOR_PREFERRED_LANGUAGE:
+                    Locale replacedLocale = LocaleList.getDefault().get(index);
+                    showDialogForPreferredLanguage(
+                            locale, replacedLocale, getSupportFragmentManager());
+                    break;
+                default:
+                    dispose(locale);
             }
         } else {
             dispose(locale);
         }
     }
 
+    private static void showDialogForSystemLanguage(
+            LocaleStore.LocaleInfo locale, FragmentManager fragmentManager) {
+        Bundle args = new Bundle();
+        args.putInt(ARG_DIALOG_TYPE, DIALOG_CHANGE_SYSTEM_LOCALE_REGION);
+        args.putSerializable(ARG_TARGET_LOCALE, locale);
+        RegionDialogFragment regionDialogFragment = RegionDialogFragment.newInstance();
+        regionDialogFragment.setArguments(args);
+        regionDialogFragment.show(fragmentManager, TAG_DIALOG_CHANGE_REGION);
+    }
+
+    private static void showDialogForPreferredLanguage(
+            LocaleStore.LocaleInfo locale, Locale replacedLocale, FragmentManager fragmentManager) {
+        Bundle args = new Bundle();
+        args.putInt(ARG_DIALOG_TYPE, DIALOG_CHANGE_PREFERRED_LOCALE_REGION);
+        args.putSerializable(ARG_TARGET_LOCALE, locale);
+        args.putSerializable(ARG_REPLACED_TARGET_LOCALE, replacedLocale);
+        RegionDialogFragment regionDialogFragment = RegionDialogFragment.newInstance();
+        regionDialogFragment.setArguments(args);
+        regionDialogFragment.show(fragmentManager, TAG_DIALOG_CHANGE_REGION);
+    }
+
+    private static int getDialogEvent(int index) {
+        if (index == -1) {
+            return DISPOSE;
+        }
+
+        return index == 0
+            ? SHOW_DIALOG_FOR_SYSTEM_LANGUAGE
+            : SHOW_DIALOG_FOR_PREFERRED_LANGUAGE;
+    }
+
+    private static int indexOfSameLanguageAndScript(Locale source) {
+        int index = -1;
+        LocaleList localeList = LocaleList.getDefault();
+        for (int i = 0; i < localeList.size(); i++) {
+            Locale target = localeList.get(i);
+            if (sameLanguageAndScript(source, target)) {
+                index = i;
+            }
+        }
+        return index;
+    }
+
     private static boolean sameLanguageAndScript(Locale source, Locale target) {
         String sourceLanguage = source.getLanguage();
         String targetLanguage = target.getLanguage();
diff --git a/src/com/android/settings/regionalpreferences/RegionDialogFragment.java b/src/com/android/settings/regionalpreferences/RegionDialogFragment.java
index 7bfc82801e6..df5c3ca54d9 100644
--- a/src/com/android/settings/regionalpreferences/RegionDialogFragment.java
+++ b/src/com/android/settings/regionalpreferences/RegionDialogFragment.java
@@ -47,9 +47,11 @@ import java.util.Set;
  */
 public class RegionDialogFragment extends InstrumentedDialogFragment {
     private static final String TAG = "RegionDialogFragment";
-    static final int DIALOG_CHANGE_LOCALE_REGION = 1;
+    static final int DIALOG_CHANGE_SYSTEM_LOCALE_REGION = 1;
+    static final int DIALOG_CHANGE_PREFERRED_LOCALE_REGION = 2;
     static final String ARG_DIALOG_TYPE = "arg_dialog_type";
     static final String ARG_TARGET_LOCALE = "arg_target_locale";
+    static final String ARG_REPLACED_TARGET_LOCALE = "arg_replaced_target_locale";
 
     /**
      * Use this factory method to create a new instance of
@@ -113,6 +115,7 @@ public class RegionDialogFragment extends InstrumentedDialogFragment {
         private final Context mContext;
         private final int mDialogType;
         private final LocaleStore.LocaleInfo mLocaleInfo;
+        private final Locale mReplacedLocale;
         private final MetricsFeatureProvider mMetricsFeatureProvider;
 
         RegionDialogController(
@@ -121,23 +124,26 @@ public class RegionDialogFragment extends InstrumentedDialogFragment {
             Bundle arguments = dialogFragment.getArguments();
             mDialogType = arguments.getInt(ARG_DIALOG_TYPE);
             mLocaleInfo = (LocaleStore.LocaleInfo) arguments.getSerializable(ARG_TARGET_LOCALE);
+            mReplacedLocale = (Locale) arguments.getSerializable(ARG_REPLACED_TARGET_LOCALE);
             mMetricsFeatureProvider =
                 FeatureFactory.getFeatureFactory().getMetricsFeatureProvider();
         }
 
         @Override
         public void onClick(@NonNull DialogInterface dialog, int which) {
-            if (mDialogType == DIALOG_CHANGE_LOCALE_REGION) {
+            if (mDialogType == DIALOG_CHANGE_SYSTEM_LOCALE_REGION
+                    || mDialogType == DIALOG_CHANGE_PREFERRED_LOCALE_REGION) {
                 if (which == DialogInterface.BUTTON_POSITIVE) {
                     updateRegion(mLocaleInfo.getLocale().toLanguageTag());
                     mMetricsFeatureProvider.action(
                             mContext,
                             SettingsEnums.ACTION_CHANGE_REGION_DIALOG_POSITIVE_BTN_CLICKED);
-                }
-                if (which == DialogInterface.BUTTON_NEGATIVE) {
+                    // TODO: add new metrics for DIALOG_CHANGE_PREFERRED_LOCALE_REGION
+                } else {
                     mMetricsFeatureProvider.action(
                             mContext,
                             SettingsEnums.ACTION_CHANGE_REGION_DIALOG_NEGATIVE_BTN_CLICKED);
+                    // TODO: add new metrics for DIALOG_CHANGE_PREFERRED_LOCALE_REGION
                 }
                 dismiss();
                 if (getActivity() != null) {
@@ -150,7 +156,7 @@ public class RegionDialogFragment extends InstrumentedDialogFragment {
         DialogContent getDialogContent() {
             DialogContent dialogContent = new DialogContent();
             switch (mDialogType) {
-                case DIALOG_CHANGE_LOCALE_REGION:
+                case DIALOG_CHANGE_SYSTEM_LOCALE_REGION:
                     dialogContent.mTitle = String.format(mContext.getString(
                         R.string.title_change_system_region),
                         mLocaleInfo.getLocale().getDisplayCountry());
@@ -161,6 +167,18 @@ public class RegionDialogFragment extends InstrumentedDialogFragment {
                         R.string.button_label_confirmation_of_system_locale_change);
                     dialogContent.mNegativeButton = mContext.getString(R.string.cancel);
                     break;
+                case DIALOG_CHANGE_PREFERRED_LOCALE_REGION:
+                    dialogContent.mTitle = String.format(mContext.getString(
+                            R.string.title_change_system_region),
+                        mLocaleInfo.getLocale().getDisplayCountry());
+                    dialogContent.mMessage = mContext.getString(
+                        R.string.desc_notice_device_region_change_for_preferred_language,
+                        mLocaleInfo.getFullNameNative(),
+                        LocaleStore.getLocaleInfo(mReplacedLocale).getFullNameNative());
+                    dialogContent.mPositiveButton = mContext.getString(
+                        R.string.button_label_confirmation_of_system_locale_change);
+                    dialogContent.mNegativeButton = mContext.getString(R.string.cancel);
+                    break;
                 default:
                     break;
             }
@@ -168,10 +186,27 @@ public class RegionDialogFragment extends InstrumentedDialogFragment {
         }
 
         private void updateRegion(String selectedLanguageTag) {
+            Locale[] newLocales = getUpdatedLocales(Locale.forLanguageTag(selectedLanguageTag));
+            LocalePicker.updateLocales(new LocaleList(newLocales));
+        }
+
+        private Locale[] getUpdatedLocales(Locale selectedLocale) {
             LocaleList localeList = LocaleList.getDefault();
+            Locale[] newLocales = new Locale[localeList.size()];
+            for (int i = 0; i < localeList.size(); i++) {
+                Locale target = localeList.get(i);
+                if (sameLanguageAndScript(selectedLocale, target)) {
+                    newLocales[i] = appendLocaleExtension(selectedLocale);
+                } else {
+                    newLocales[i] = localeList.get(i);
+                }
+            }
+            return newLocales;
+        }
+
+        private Locale appendLocaleExtension(Locale selectedLocale) {
             Locale systemLocale = Locale.getDefault();
             Set<Character> extensionKeys = systemLocale.getExtensionKeys();
-            Locale selectedLocale = Locale.forLanguageTag(selectedLanguageTag);
             Locale.Builder builder = new Locale.Builder();
             builder.setLocale(selectedLocale);
             if (!extensionKeys.isEmpty()) {
@@ -179,13 +214,21 @@ public class RegionDialogFragment extends InstrumentedDialogFragment {
                     builder.setExtension(extKey, systemLocale.getExtension(extKey));
                 }
             }
-            Locale newLocale = builder.build();
-            Locale[] resultLocales = new Locale[localeList.size()];
-            resultLocales[0] = newLocale;
-            for (int i = 1; i < localeList.size(); i++) {
-                resultLocales[i] = localeList.get(i);
+            return builder.build();
+        }
+
+        private static boolean sameLanguageAndScript(Locale source, Locale target) {
+            String sourceLanguage = source.getLanguage();
+            String targetLanguage = target.getLanguage();
+            String sourceLocaleScript = source.getScript();
+            String targetLocaleScript = target.getScript();
+            if (sourceLanguage.equals(targetLanguage)) {
+                if (!sourceLocaleScript.isEmpty() && !targetLocaleScript.isEmpty()) {
+                    return sourceLocaleScript.equals(targetLocaleScript);
+                }
+                return true;
             }
-            LocalePicker.updateLocales(new LocaleList(resultLocales));
+            return false;
         }
 
         @VisibleForTesting
diff --git a/src/com/android/settings/regionalpreferences/RegionPickerBaseListPreferenceController.java b/src/com/android/settings/regionalpreferences/RegionPickerBaseListPreferenceController.java
index c06c6695220..fc12d1baa3f 100644
--- a/src/com/android/settings/regionalpreferences/RegionPickerBaseListPreferenceController.java
+++ b/src/com/android/settings/regionalpreferences/RegionPickerBaseListPreferenceController.java
@@ -169,7 +169,7 @@ public abstract class RegionPickerBaseListPreferenceController extends BasePrefe
         mFragmentManager = mParent.getChildFragmentManager();
         Bundle args = new Bundle();
         args.putInt(RegionDialogFragment.ARG_DIALOG_TYPE,
-                RegionDialogFragment.DIALOG_CHANGE_LOCALE_REGION);
+                RegionDialogFragment.DIALOG_CHANGE_SYSTEM_LOCALE_REGION);
         args.putSerializable(RegionDialogFragment.ARG_TARGET_LOCALE, localeInfo);
         RegionDialogFragment regionDialogFragment = RegionDialogFragment.newInstance();
         regionDialogFragment.setArguments(args);