SOLVED Same password works here but not there

[So Here I Am]

I'm on a 2014 Mac Air, up to date with Big Sur.

My Apple ID and password are working just fine on the App Store and in Preferences.

But when I go to appleid.apple.com, it won't accept the same password. It just won't. I've moved right from the App Store to the appleid front page - with the same password copied to paste. It works in one place and not the other.

Any idea what the problem might be/?

 

[Jaxibell]

Me too

 

[So Here I Am]

Jaxibell, after a long time on the phone with an excellent AppleCare agent, here's what finally worked in my case:

When you try to log into an Apple.com page, there's a pop-up for your password. If your passwords on Safari and Firefox are protected, there's a pop-up when you try to log in to an apple.com page, so you can authorize your password being filled in. They are almost identical.

So: enter your Apple user id, and you'll get a pop-up asking for the password. But it's not the apple.com password it wants. It wants your Mac password to authorize filling in the Apple password.

Fill in your Mac password, the Mac will fill in the Apple password, and Bob's your uncle - fixed!

Good luck.