每当我单击精灵时，屏幕状态都会恢复

我正在尝试在Xna 4.0中制作游戏，但我坚持使用游戏菜单。

    protected override void Update(GameTime gameTime)
    {
        MouseState ms = Mouse.GetState();
        // Allows the game to exit
        if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
            this.Exit();
        if (ms.LeftButton == ButtonState.Pressed && ((ms.X >= 280 && ms.X <= 540) && (ms.Y >= 150 && ms.Y <= 200)))
            current_screen = ScreenState.Difficulty;
        if (current_screen == ScreenState.Title)
        {
            if (ms.LeftButton == ButtonState.Pressed && ((ms.X >= 280 && ms.X <= 540) && (ms.Y >= 360 && ms.Y <= 410)))
                this.Exit();
        }
        if (current_screen == ScreenState.Difficulty)
        {
            if (ms.LeftButton == ButtonState.Pressed && ((ms.X >= 300 && ms.X <= 520) && (ms.Y >= 100 && ms.Y <= 130)))
                current_screen = ScreenState.Title;
            if ((ms.LeftButton == ButtonState.Pressed && oldMouseState.LeftButton == ButtonState.Released) && ((ms.X >= 280 && ms.X <= 540) && (ms.Y >= 150 && ms.Y <= 200)))
            {
                current_screen = ScreenState.MainGameNovice;
            }
        }
        base.Update(gameTime);
        oldMouseState = ms;
    }
    protected override void Draw(GameTime gameTime)
    {
        GraphicsDevice.Clear(Color.CornflowerBlue);
        spriteBatch.Begin(SpriteSortMode.BackToFront, BlendState.AlphaBlend);
        switch (current_screen)
        {
            case ScreenState.Title:
                spriteBatch.Draw(mybg, GraphicsDevice.Viewport.Bounds, Color.White);
                spriteBatch.Draw(new_game_button, new Vector2(280, 150), Color.White);
                spriteBatch.Draw(load_game_button, new Vector2(280, 220), Color.White);
                spriteBatch.Draw(how_to_play_button, new Vector2(280, 290), Color.White);
                spriteBatch.Draw(quit_game_button, new Vector2(280, 360), Color.White);
                break;
            case ScreenState.Difficulty:
                spriteBatch.Draw(diff_bg, GraphicsDevice.Viewport.Bounds, Color.White);
                spriteBatch.Draw(novice_button, new Vector2(280, 150), Color.White);
                spriteBatch.Draw(inter_button, new Vector2(280, 220), Color.White);
                spriteBatch.Draw(expert_button, new Vector2(280, 290), Color.White);
                break;
            case ScreenState.LoadGame:
                break;
            case ScreenState.HowtoPlay:
                break;
            case ScreenState.MainGameNovice:
                //main game
                spriteBatch.Draw(expert_button, new Vector2(580, 290), Color.White);
                break;
            case ScreenState.MainGameIntermediate:
                ///main game
                break;
            case ScreenState.MainGameExpert:
                ////Main game
                break;
        }
        spriteBatch.End();
        base.Draw(gameTime);
    }

每当我单击新游戏按钮时，它都会显示难度级别。
问题是当我单击新手按钮时，它不会转到看起来像纯蓝屏的屏幕。它会通过它，并在几秒钟内返回难度级别菜单。你能帮帮我吗？我被困在这里大约一天了，我已经搜索了与此类似的问题，但仍然不起作用。