If I'm picturing the situation correctly ... The deal is that if you were to tighten the screws all the way, the outlet would be set into the wall and not flush with the plate ... ?
You can buy spacers that will bring the outlet out from the box. You can ask someone at a hardware store for help - they may have heard of them (describe the problem to them.)
Basically, it's a plastic spacer that goes on the mounting screw - Screw goes through receptacle, through spacer, and then into the box. (You may need longer screws than what's there now.) You could substitute "something else" for the spacer if you can't find one specifically sold for that purpose.