First, I found this answer very helpful. What was most helpful was the statement from the help document:
The roaming signatures feature will be available to users with mailboxes on Microsoft 365 or Outlook.com. Accounts hosted on Exchange on-premises servers, with third-party email services, or utilizing POP/IMAP accounts will not be able to roam their signatures at this time.
I have 14 email addresses - all in Outlook. Some are POP. Some are on Exchange. Some are third party. So what Microsoft did was take away my ability to edit any signatures on Outlook. I'm not happy!!!!! This is HORRENDOUS!!! Even worse than when they took away the variety of colors that previously were available for categories! I can't believe how idiotic this change is, or how devastating it is to lose the ability to edit my signatures or make new ones on my device simply because the idiots at Microsoft thought everyone wanted roaming signatures. Why would they take that ability away? Not everyone wants to use web-based email!
I did figure out that a few of my signatures can still be edited - the ones that are associated with certain accounts. But most of them are dead in the water - I can't edit them, I can't recreate them, I can't do anything with them.
Horrible, horrible, horrible decision.
CJ