List Preference default value not working Android studio

I am trying to set up the default value for the list preferences in my app, but I am having trouble with the default value, as when I try to run the app the default values that I chose in both list preferences are not being selected in runtime. This is my xml code:

<PreferenceScreen xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:android="http://schemas.android.com/apk/res/android">

    <PreferenceCategory app:title="@string/display_header">

        <ListPreference
            app:key="language"
            android:title="@string/language_title"
            app:summary="@string/en"
            android:entries="@array/lang_entries"
            android:entryValues="@array/lang_values"
            android:defaultValue="@string/en"
            />

        <ListPreference
            app:key="display"
            app:title="@string/display_mode_title"
            app:entries="@array/display_entries"
            app:entryValues="@array/display_values"
            app:summary="@string/automatic"
            android:defaultValue="@string/automatic"/>

    </PreferenceCategory>


</PreferenceScreen>

I tried uninstalling and reinstalling the app but it did not work. I also checked that the string names that I used in the default value are correct, and I also made sure that the default value matches the one in the string array of entries. Please help me fix this problem

I just found out that I had to replace the android:defaultValue line by app:defaultValue and I had to pass the corresponding value to the entry that would be the default value in runtime.