Set up toolbar as actionbar in fragment

try:

 ((AppCompatActivity)getActivity()).setSupportActionBar(toolbar);

ActionBar is an Activity property. If you want to set a toolbar from a given fragment as the ActionBar of the owning Activity, then get the Activity that owns the fragment (Fragment.getActivity()) and set its ActionBar property.

Then juse use the same setDisplayHomeAsUpEnabled method you mentioned to begin with on the ActionBar after setting your toolbar as the ActionBar to get the back / up button.

You will obviously have to manage this carefully if your app has multiple fragments within that Activity.

Use

((ActionBarActivity) getActivity()).getSupportActionBar().setSubtitle("Your Title");

Now ActionBarActivity is deprecated so You need to cast your activity from getActivity() to AppCompatActivity first. Here's an example:

((AppCompatActivity) getActivity()).getSupportActionBar().setSubtitle();

The reason you have to cast it is because getActivity() returns a FragmentActivity and you need an AppCompatActivity