I've changed my Apple ID email address, can't use iCloud
I recently changed the email address for my Apple iCloud account, which means I now have a new Apple ID (terrible idea, making the ID your email address - this has been a big no-no in the online world for years). I was then unable to use any app that was formerly tied to my iCloud account, which used the old ID. I finally was able to log out of the old ID on my iPad and sign back in with the new one (it said it would merge everything - no problems yet).
Unfortunately, things aren't so easy on my iMac. I continue to get the iCloud popup that asks for my Apple ID ... for my old email/ID. I want to log out of the old address and log in with the new one, but I get the very scary warning that this will erase all photos, calendar events, documents, etc., *on my iMac*. What the heck?
So, I'm stuck. Is there another way to do this?
iMac, OS X Mavericks (10.9.2)