如何在Xamarin中更改TextView中的文本？

Question

Main_Activity

[Activity(Label = "Project", MainLauncher = true)]
public class Main_Activity : Activity
{
    protected override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);
        RequestWindowFeature(WindowFeatures.NoTitle);

        // Set our view from the "main" layout resource
        SetContentView(Resource.Layout.Main_Layout);

        ImageButton _Back_Button = (ImageButton)FindViewById(Resource.Id._Back_Button);
        TextView _Title_Text = (TextView)FindViewById(Resource.Id._Title_Text);
        ImageButton _Exit_Button = (ImageButton)FindViewById(Resource.Id._Exit_Button);

        _Title_Text.Text = "Setting";

        FragmentTransaction _Setting_Content_Adatper = this.FragmentManager.BeginTransaction();
        Project.Fragments.Setting_Content_Fragment _Setting_Content = new Project.Fragments.Setting_Content_Fragment();
        _Setting_Content_Adatper.Replace(Resource.Id._Adapter_Content, _Setting_Content);
        _Setting_Content_Adatper.Commit();

        _Back_Button.Click += (s, e) =>
        {
            _Title_Text.Text = "Setting";

            FragmentTransaction _Main_Fragment = this.FragmentManager.BeginTransaction();
            Project.Fragments.Setting_Content_Fragment Setting_Main_Fragment = new Project.Fragments.Setting_Content_Fragment();
            _Main_Fragment.Replace(Resource.Id._Adapter_Content, Setting_Main_Fragment);
            _Main_Fragment.AddToBackStack(null);
            _Main_Fragment.Commit();
        };

        _Exit_Button.Click += (s, e) =>
        {
            Finish();
        };
    }
}
}

Setting_Fragment：

public class Setting_Content_Fragment : Fragment
{
    public override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);

        // Create your fragment here
    }

    public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        View _Setting_Content = inflater.Inflate(Resource.Layout.Setting_Content_Layout, container, false);

        Button _General_Button = (Button)_Setting_Content.FindViewById(Resource.Id._btnGeneral);

        LayoutInflater _Change = (LayoutInflater)Activity.GetSystemService(Context.LayoutInflaterService);
        View _Change_Text = _Change.Inflate(Resource.Layout.Main_Layout, null);
        TextView _Title_Text = (TextView)_Change_Text.FindViewById(Resource.Id._Title_Text);

        _General_Button.Click += (s, e) =>
        {
            _Title_Text.Text = "General";

            FragmentTransaction _Main_Fragment = this.FragmentManager.BeginTransaction();
            Project.Fragments.General_Content.General_Main_Fragment General_Main_Fragment = new Project.Fragments.General_Content.General_Main_Fragment();
            _Main_Fragment.Replace(Resource.Id._Adapter_Content, General_Main_Fragment);
            _Main_Fragment.Commit();
        };

        return _Setting_Content;
    }
   }
}

现在从Setting_Fragment中调用Main_Active中的TextView。

当我按下Setting_Fragment上的按钮时，我想更改TextView中的文本。

我无法做到。

这应该是什么解决办法？