Thanks, Tim!
The navigation that I was looking for was in your reply: Profiles tab, then on that opening screen, look in the second blue box at the right, second option is ta da "Manage Seller Details." I click on that, and there are my Seller Detail profies, with the copy, edit, delete buttons. Perfect!
I never noticed that before, and am delighted that I can skip that whole rigamarole I described to manage my SD profiles.
You da man!
Best,
Wilbere