My Samsung S4 Is Playing up Help?

[AC Question]

Every time I hit the back button on my phone it's just acting werid. It would go back but than I would be on my home screen and google would randomly pop up. When I'm in facebook the menu button comes up randomly. When I'm in settings help would come up when I didn't want it to. And when I would be on my homes screen my window there would zoom in and out. Does anyone know how to fix it?

 

[the tall guy]

Hi, have you dropped or damaged the screen on the phone? have you rooted the device?