Fragment title remain on previous fragments title when I press back button

Question

By following this and this MO posts I tried to set title of app bar of my android project as follow:

MainActivity

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main_activity);
        setSupportActionBar(findViewById(R.id.toolbar));

        navController = Navigation.findNavController(this, R.id.navHostFragment);
        navController.addOnDestinationChangedListener((controller, destination, args) -> {
            // Check if it's a root destination
            NavGraph destinationGraph = destination.getParent();
            boolean isRootDestination = destinationGraph != null &&
                    destinationGraph.getStartDestinationId() == destination.getId();
            // Update back button accordingly
            Objects.requireNonNull(getSupportActionBar())
                    .setDisplayHomeAsUpEnabled(!isRootDestination);

            // Update activity title
            setTitle(destination.getLabel());
        });
    }

---

fragments_Graph.xml

<fragment
    android:id="@+id/fragmentA"
     ...
    android:label="Fragment A"
    ... >
    <action
        android:id="@+id/action_fragmentA_to_fragmentB"
        app:destination="@id/fragmentB"
        app:launchSingleTop="true" />
</fragment>
<fragment
    android:id="@+id/fragmentB"
    ...>
    <action
        android:id="@+id/action_fragmentB_to_fragmentA"
        app:destination="@id/fragmentA"
        app:launchSingleTop="true" />
</fragment>

and inside of onCreate of Fragment B i used:

requireActivity().setTitle("some title");

everything is working fine in forward direction but when I press back arrow in Fragment B, Title of Fragment A become "some title"!! What is the problem??

When I add another fragment with predefined title (in graph.xml, i.e. android:label="Fragment New") before Fragment A, navigating up and back between fragments A and New one work fine and AppBar title show what specified.

Update:

I tried to use the following but the issue remains the same (i.e. Fragment A -> New Label! (fragment B), and in back direction: New Label! -> New Label! (fragment A) ):

if(destination.getLabel()==null){
   destination.setLabel("New Label!");
   setTitle(destination.getLabel());
} else {
   setTitle(destination.getLabel());
}