While encountering an enemy, the game put up a multiple choice box, I chose dive to periscope depth. There was also a small checkbox for making it the default action, which like an idiot I checked.
I ended up chasing a merchant ship and the game went to periscope depth but I was unable to catch up to the merchant submerged and couldn't surface as long as there was contact!
I haven't been able to find a way to turn off the default action. Do I start another career or is there another way? Thanx!