iPhone notes-changing email address

Notes on my iPhone 15 Pro are set up under an old Hotmail address I no longer have. I can’t seem to change this address. I did for my Apple ID though. Notes here still save to iCloud but I can’t move them to Gmail notes I set up and I can’t make folders there. If I make notes under Gmail account nothing is saved to iCloud. They are only saved if I move them to iPhone notes but I do want to be able to access them on all devices. The Apple Store couldn’t help me. Is it because Gmail accounts are not compatible? How do I change or delete this hotmail address?

[Edited by Moderator]