Hey jobrooke
welcome to the forum!
It depends on what size you are to begin with, because if you don’t have enough breast tissue the surgeon will have to do unders, which is under the muscle in your breast. Overs is where the implant is placed over the muscle inside your breast. There are disadvantages and advantages to both! Overs I’ve heard heal quicker as the muscle isn’t pressing on the implant. I think it depends on your body shape and what kind of look you want to achieve!
hope this helps i’m sure lots of other girls will reply with a better explanation lol xx