Help with Partial Shoulder Dislocation.?

I think I might have damaged my shoulders when I was younger, I think it was a skateboarding accident where I fell and might have dislocated my shoulders because the back of my shoulders, the area where the back tendon behind the armpit was bruised and it hurt alot. I don't remember if both shoulders were bruised but now I get reoccuring dislocations, ones that don't hurt all that much and I can put back in myself but it really annoys me when I'm playing sports. The dislocation seems to be if I accidently hyper extend my arm too far back and up. What are ways I could fix this? Weight training, resistance training? I really wouldn't like to do a surgery...