Hi there, Valerie. I appreciate the details and your effort to troubleshoot this.
That error message appears when QuickBooks Online (QBO) thinks two people are editing the same page simultaneously. Since you are the only user, the system is mistaking a duplicate tab, or a different browser running in the background for a second person. It is also possible that a previous session didn't close properly, leaving a ghost session on the server that is now blocking your current changes.
To fix this, close all QuickBooks tabs and log in via a Private or Incognito window to force a fresh session. Should the issue persist, log out entirely for 30 minutes to allow the servers to automatically reset your account access.
To prevent this in the future, it's a great practice to use the official Sign Out button rather than just closing your browser tab. This signals the server to unlock your settings immediately. Additionally, avoid opening QuickBooks in different browsers or multiple tabs simultaneously, as the system may view these as separate users and prevent you from saving your changes.
Let us know if you have any other questions or concerns about managing your settings or account by replying to this post.