icloud popup asking me to sign in with an old email address

Hi! I recently signed into icloud to manage my storage and a new continuous popup keeps asking me to sign in under my old email address (I'm already signed in under new email). This is only happening on my home computer. It won't let me change the email address to the new one. It keeps popping up over and over and is so annoying. If anyone can help how I can stop this I would greatly appreciate it! Its popped up twice while I type this. Thank you!