Haha I was gonna say that; righty tighty, lefty loosey.
Also when unscrewing it's always worth just turning each screw a tiny bit to loosen them up, sometimes leaving just one screw in makes it lock into the thread more and is a nightmare to get out.
Thats a good tip from rounddoger, yes because by taking the screws out the pcb will lift slightly putting that extra bit pressure on that screw.