I think I'm on the right tracks but need some help/confirmation.
What email address shows to customers - primary or other? I understand that the different emails can be used for different websites or payment scenarios so you know the source. The old primary has been used with sandbox and test purchase but is now demoted as I have a new primary. Do I use the the new primary on the website or stay with the old one?
Any forum help or direction to a proper tutorial on this above and beyond the basic instructions which I already know would be most welcome.