How to Correctly Reference a Method in App.xaml.cs

    public partial class Settings : UserControl
    {
        public Settings()
        {
            InitializeComponent();
        }

        private void OnLanguageChanged(object sender, SelectionChangedEventArgs e)
        {
            string? selectedLanguage = ((ComboBoxItem?)e.AddedItems[0]).Tag.ToString();
            Debug.WriteLine(selectedLanguage);
            ((App)Application.Current).ChangeLanguage(selectedLanguage);
        }
    }
}

public partial class App : Application
{
    public void ChangeLanguage(string language)
    {