Hi pattycyn!
When you say you had to "choose" them again, do you mean you had to check the box again, or did you have to go and select each gallery image again? If you mean you just had to check the box again, that is how it is supposed to work. If that isn't what you meant, were you editing an existing Saved listing, or creating a brand new on from scratch? If we know where it was not working we can get it fixed a lot quicker for ya.
There is no account preference for that option, but is something we hope to add in the future. For right now, all you have to do is check that box to enable them on the lister, and that's it.