How to Enable Backstack for Fragment using Navigation Comp. Lib

Question

my question related only to the new Library from google Navigation Component library, so it's not related to the regular fragment like .addtobackstack and so on.

I will simplify what I wanna do, but my app has +30 fragment

we have a Parent fragment and child one Parent Fragment has tabs and recycler view and data comes from API. if I clicked on an RV item will Open child fragment. if I returned to the parent fragment I wanna it like it was, I don't wanna load data again.

my tests always reload again from the beginning, create views and then load the data, I wanna it like when we open new activity with intent, the parent activity still has his own views.

This is some of my code maybe I have an issue

   val host: NavHostFragment = supportFragmentManager
            .findFragmentById(R.id.main_activity_host_fragment) as NavHostFragment? ?: return 

class ParentFragment : Fragment() {
    var mEmail: String = ""
    var mPassword: String = ""
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

    }

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        var rootView: View = inflater.inflate(R.layout.fragment_parent, container, false)

setupViews(rootView)
        loadDataFromServer()

        rootView.text_clickable_to_sign_up_from_sign_in.setOnClickListener {
            findNavController().navigate(R.id.child_frag_dest, null, null)
        }
        return rootView

    }}
...