My taskbar doesn't hide in full screen when i watch youtube videos


Whenever i go fullscreen in YouTube or any other video site my taskbar doesn't hide. I change the browser from Chrome to Opera same thing.  After i replaced Bitdefender free 2017  everything works normal ! Somehow the browser is affected !


My security : Bitdefender free,Malwarebytes free


OS: Windows 7 Sp1


The sistem is clean.