Catalina keychain looping ****

Hello helpful persons,

I just updated to Catalina and immediately began having keychain problems, with constant requests to enter my password on my phone, iPad, iMac, phone again, all day long for the past few days. I sat down to try and resolve it today. One suggestion I saw was to go into the iCloud settings on my iMac and uncheck the keychain access box, restart my computer, then recheck the box to reestablish the link between iCloud and keychain.

But when I check the box to turn it back on, it now asks me to "review and upgrade my Apple ID security", then tried to force me to create a new Apple ID password. Unnecessary, but when I go along with it and try to create a new password, it tells me the current "old" password is incorrect, and gives no other options than "cancel." My password is not incorrect, I just used it one second ago to sign into iCloud.

Any ideas what exactly is wrong here, or how to solve this?

What I've tried: I've restarted. I've logged out of iCloud and logged back in again. I tried the password for my desktop in the event it was asking for that and not my Apple ID.

Thank you in advance for your help. -Karen