How to observe data from live data android on Three different Fragment

Hey guys I have my Activity MainActivity.kt .

And and one ViewModel MainActivityViewModel.kt

And I want to observe my live data to my 3 different fragments.

class MainActivity{

      lateinit var mainActivityViewModel: MainActivityViewModel
      ...

     mainActivityViewModel = ViewModelProviders.of(this, viewModelFactory).get(MainActivityViewModel::class.java)
}

class MainFragmentOne{

      lateinit var mainActivityViewModel: MainActivityViewModel
      ...

     mainActivityViewModel = ViewModelProviders.of(this, viewModelFactory).get(MainActivityViewModel::class.java)
}

But my observer only work on activity not on the fragments.

from How to observe data from live data android on Three different Fragment