See here how to deal with Fix Account in Shared Experiences Settings:
https://www.windowsdigitals.com/microsoft-account-problem-notification-message-popup-windows-10/
(Note: This is a third-party link and we do not have any guarantees on this website. And Microsoft does not make any guarantees about the content.)
Feel free to ask back any questions and let us know how it goes. I will keep working with you until it's resolved.
Best regard,
Sylvia