Hi Chris_V89,
Thanks for your response. I'm being asked to sign in with a previous email that was a part of my Apple ID for years until some months ago--I changed to a new ID and that pre-dated my icloud pop up issues by several months. Although I didn't know I was supposed to do anything after changing my ID, the correct ID shows up on my phone and I can use the new ID to sign in to icloud.com on my windows pc. As I think I noted, the email on the popup can't be changed, but I can select something saying I have forgotten my apple ID or password. But I am very leery of trying to set up something totally new when it's the popup that's the problem. I read somewhere that I should download an iCloud for windows app, but I've been unsuccessful at that & don't know how that would help since I can sign in to icould.com on my pc. Anyway, I am now going to follow your advice and contact Apple support. I just went to our state's only Apple store earlier in the week about a phone issue--can't believe I didn't ask about this annoying problem when I was there! Thanks so much for being willing to try to help.