Implants replaced. Under muscle to over muscle? (Photo)

I’ve had my current implants for almost 19 years and I’d rather redo them now before something happens. I’ve been debating whether I want to switch them from under the muscle to over the muscle due to breast distortion when flexing. This is probably to much information (TMI) but I hate when they move and distort while having sex especially when we are in positions where I have to use my arms strength to hold myself up. I have quite a bit of natural breast tissue.