@sheldrake
Re. "Sign & Save", I think you worked this one out for yourself. Although it shouldn't confuse in the first place of course. On us.
Signing is essential to give you the warm glow of knowing it's exactly what you think it is even though you've not used the address in question it in six months. Safe. Secure.
But because it's a bit of effort, it makes sense to allow you to make many additions and/or edits before signing them all the once.