返回上一个片段后，应用标题保持不变

我一直在开发一个Android应用程序，其中包括Android Studio中的默认导航抽屉等。在我的家庭片段中，我实现了CarViews，然后将这些cardview设置为OnClickListener以用传统过程替换该片段。在片段替换和新页面到来之后，我想更改操作栏标题。所以onCreateView(...)我尝试了

((AppCompatActivity)getActivity()).getSupportActionBar().setTitle("B");

有效。但是，按下硬件后退按钮返回到堆叠的片段后，标题仍保持更改且不再更改"Home"。我尝试了其他方法。这是我的以下代码。提前致谢。

public class HomeFragment extends Fragment implements View.OnClickListener {
    public View onCreateView(@NonNull LayoutInflater inflater,
                             ViewGroup container, Bundle savedInstanceState) {
        View root = inflater.inflate(R.layout.fragment_home, container, false);
        Objects.requireNonNull(((AppCompatActivity) Objects.requireNonNull(getActivity())).getSupportActionBar()).setTitle("Home");

        CardView cardView1 = root.findViewById(R.id.doctor_on);
        CardView cardView2 = root.findViewById(R.id.ambulance_e);
        CardView cardView3 = root.findViewById(R.id.maintainance_s);

        cardView1.setOnClickListener(this);
        cardView2.setOnClickListener(this);
        cardView3.setOnClickListener(this);

        return root;
    }

    @Override
    public void onClick(View v) {
        int id = v.getId();
        switch (id) {
            case R.id.doctor_on:
                FragmentTransaction fragmentTransaction = Objects.requireNonNull(getActivity()).getSupportFragmentManager().beginTransaction();
                Fragment fragment1 = new doctors();
                fragmentTransaction.replace(R.id.container1, fragment1).addToBackStack(getString(R.string.menu_home)).commit();
                return;
            case R.id.ambulance_e:
                //Put Actions
                FragmentTransaction fragmentTransaction2 = Objects.requireNonNull(getActivity()).getSupportFragmentManager().beginTransaction();
                Fragment fragment2 = new ambulance();
                fragmentTransaction2.replace(R.id.container1, fragment2).addToBackStack(getString(R.string.menu_home)).commit();
                return;
            case R.id.maintainance_s:
                //Put Actions
                FragmentTransaction fragmentTransaction3 = Objects.requireNonNull(getActivity()).getSupportFragmentManager().beginTransaction();
                Fragment fragment3 = new maintanance();
                fragmentTransaction3.replace(R.id.container1, fragment3).addToBackStack(getString(R.string.menu_home)).commit();
                return;
        }
    }

    @Override
    public void onResume() {
        super.onResume();
        ((AppCompatActivity) getActivity()).getSupportActionBar().setTitle("Home");
    }
}

到下一个片段（我在其中更改标题栏并按返回按钮）：

public class doctors extend Fragment{
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        ((AppCompatActivity)getActivity()).getSupportActionBar().setTitle("B");
        View root = inflater.inflate(R.layout.fragment_doctors, container, false);

        return root;
    }

}