SharedPreferences not working when trying to update TextView

I'm trying to change a TextView and I want it to be permanent, so I'm using SharedPreferences. Sadly, something is wrong, because the TextView doesn't update.

MainService:

private void updateUI(Intent intent) {
    String counter = intent.getStringExtra("counter");
    TextView txtCounter = (TextView) findViewById(R.id.txtCounter);
    assert txtCounter != null;

    SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(MainActivity.this);
    SharedPreferences.Editor editor = preferences.edit();
    editor.putString(String.valueOf(txtCounter), counter);
    editor.commit();
}