Think you own the place - Idioms by The Free Dictionary
think you own the place
think (one) owns the place
To behave in a haughty, arrogant, or imperious manner. The contractor they hired must think he owns the place, judging by the way he's telling us all how to do our jobs!
think you ˈown the place (also behave/act as if you ˈown the place) (disapproving) behave in a very confident way that annoys other people, for example by telling them what to do: What does she think she’s doing, coming in here acting as if she owns the place!