Android Question Full Screen (immersive-mode) Not working when Admob (InterstitialAd or RewardedVideoAd)


I make my application work in full screen mode by following this thread:

but after I add admob ads as the following:

I had a problem ...full screen work normally with banner because its a normal view I think...
but Navigation buttons (Back and home ..buttons) return to screen when application shows (InterstitialAd or RewardedVideoAd)

question is : How can I hide the navigation and return to full screen when show InterstitialAd or RewardedVideoAd