[UPDATE PG. 3] Peeing while changing.

I suppose you have been doing the 24/7 thing for a significant long time. Two things tend to happen. First is that you condition the mind to ignore the onset of urine pressure and leave the sphincter muscles open. Second is that you cause an atrophy to occur in those muscles from lack of use. The combination makes it very difficult to control it. Puts you into a situation not unlike that of a toddler learning to stay dry. It can probably be reversed, but it will take some serious potty training.

Update here.