Try using an adjustable bench and put it on the 2-3 hole. I don't like how high the fixed ones are. They put a lot of stress on my rotators. So I put it about half way between a flat and the fixed incline height. Always remember to lower the bar slowly under control. I see some guys damn near let the bar drop on them, and then they have legs flying all over the place trying to hump the bar up lol.
To increase the strength in the stabilizer muscles I recommend Stop with bench press and start using dumbbells for all your lifts it will take into account individual side and will not require spotters till you get a heavy weight and will help build stabilizing muscles.