Cho mình hỏi về Youtube Fragment với

Hiện tại thì mình đang dùng Youtube Fragment khi bấm nút back thì nó tự động đóng cái Fragment Youtube lại bấm lần nữa mới thoát ra khỏi Activity, các bạn hỗ trợ mình với ý của mình là khi bấm back là phải thoát khi khỏi Activity liền

Class HelloAndroid 
public class HelloAndroid extends AppCompatActivity {
    TextView tvPar;
    Toolbar toolbar;
    int i;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_hello_android);
        toolbar = (Toolbar) this.findViewById(R.id.toolbar_android_co_ban_manager);
        setSupportActionBar(toolbar);
        getSupportActionBar().setDisplayShowTitleEnabled(false);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);

        HelloFragmentYoutube fragment = new HelloFragmentYoutube();
        FragmentManager manager = getSupportFragmentManager();
        manager.beginTransaction()
                .replace(R.id.main, fragment)
                .addToBackStack(null)
                .commit();

    }
}

Class HelloFragmentYoutube
public class HelloFragmentYoutube extends Fragment {

    // API キー
    private static final String API_KEY = "AIzaSyDSgkbxq_TZJk62gUOdxKWDUKLXOQmS5cs";

    // YouTubeのビデオID
    private static String VIDEO_ID = "R742C9tIp8E";

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_hello_fragment_youtube, container, false);

        // YouTubeフラグメントインスタンスを取得
        YouTubePlayerSupportFragment youTubePlayerFragment = YouTubePlayerSupportFragment.newInstance();

        // レイアウトにYouTubeフラグメントを追加
        FragmentTransaction transaction = getChildFragmentManager().beginTransaction();
        transaction.add(R.id.youtube_layout, youTubePlayerFragment).commit();

        // YouTubeフラグメントのプレーヤーを初期化する
        youTubePlayerFragment.initialize(API_KEY, new YouTubePlayer.OnInitializedListener() {

            // YouTubeプレーヤーの初期化成功
            @Override
            public void onInitializationSuccess(YouTubePlayer.Provider provider, YouTubePlayer player, boolean wasRestored) {
                if (!wasRestored) {
                    player.setPlayerStyle(YouTubePlayer.PlayerStyle.DEFAULT);
                    player.loadVideo(VIDEO_ID);
                    player.play();
                }
            }

            // YouTubeプレーヤーの初期化失敗
            @Override
            public void onInitializationFailure(YouTubePlayer.Provider provider, YouTubeInitializationResult error) {
                // YouTube error
                String errorMessage = error.toString();
                Toast.makeText(getActivity(), errorMessage, Toast.LENGTH_LONG).show();
                Log.d("errorMessage:", errorMessage);
            }
        });

        return rootView;
    }
}