Muting Sounds in Android App with Shared Preferences Not Working

I'm building my first Android app, so apologies in advance for my lack of expertise. I've been banging away at this issue for 2 days so far. When I set the sound to mute in my Settings Activity via Shared Preferences, the setting does not 'stick'. Here is the code from my Main Activity:

SharedPreferences settingsSP;
boolean muteSound;

Then in onCreate:

settingsSP = getApplicationContext().getSharedPreferences("PlayerPreferences", Context.MODE_PRIVATE);
muteSound = settingsSP.getBoolean("muteSound", false);

Then I obviously use the muteSound variable to determine whether or not to play sounds within the MainActivity. Now when I go the Settings activity I have this code:

SharedPreferences settingsSP;
boolean muteSound;

Then in onCreate I have this:

settingsSP = getApplicationContext().getSharedPreferences("PlayerPreferences", Context.MODE_PRIVATE);


if (muteSound) {
      activitySettingsBinding.displayMuteCheckBox.setChecked(true);      
} else {
      activitySettingsBinding.displayMuteCheckBox.setChecked(false);     
}


activitySettingsBinding.displayMuteCheckBox.setOnClickListener(v -> {

    if (activitySettingsBinding.displayMuteCheckBox.isChecked()) {

        muteSound = true;

        SharedPreferences.Editor editor = settingsSP.edit();
        editor.putBoolean("muteSound", muteSound);
        editor.apply();

    } else {

        muteSound = false;

        SharedPreferences.Editor editor = settingsSP.edit();
        editor.putBoolean("muteSound", muteSound);
        editor.apply();

        soundPool.play(bubble, 1, 1, 1, 0, 1);

}

The xml code:

<CheckBox
                    android:id="@+id/displayMuteCheckBox"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_marginStart="40dp"
                    android:gravity="center_vertical"
                    android:layoutDirection="rtl"
                    android:paddingLeft="40dp"
                    android:paddingTop="16dp"
                    android:paddingBottom="16dp"
                    android:text="Mute Sound"
                    android:textColor="#FFFFFF"
                    android:textSize="20sp"
                    android:textStyle="bold"
                    android:theme="@style/CheckBoxStyle" />

I placed a number of log.d tags throughout the code so that I observe what was happening. For example after I cold booted the app in Android Studio:

• Open MainActivity, onCreate muteSound = false
• Tap Settings button and the Settings onCreate lists muteSound = false
• I check the checkbox to set it to muteSounds = true
• I tap return button within Settings to return to MainActivity
• MainActivity onCreate muteSound = true
• Tap Settings button and the Settings onCreate lists muteSound = false
• And the checkbox is unchecked - because muteSound = false

I can't figure out why the settings is not sticking. When I checked to set the muteSound to be true, that settings is lost when I return to the Settings Activity. I've searched the code to see if I set muteSound = true on accident somewhere else, but when searching the usages I did not find any. Is my assumption about sharePreferences incorrect. It doesn't appear to hold the settings. Or perhaps am I using the checkbox incorrectly, maybe I should be using another type of button here. I would like to use checkboxes to control the display of the score, time and other items on the MainActivity and throughout other app Activities, but if I can't figure this gap in my knowledge I won't be able to. What am I doing incorrectly?