If you're getting a message that says "Sorry another account from your organization is already signed in on this computer." when using Microsoft 365, here's how to fix it:
Sign Out of All Microsoft 365 Applications
Clear Saved Sign-In Information:
Reboot the PC, and then sign in to Microsoft 365 Account again
Extra troubleshooting steps here: https://docs.microsoft.com/en-us/office/troubleshoot/office-suite-issues/another-account-already-signed-in
If you still require assistance, please contact the IT Service Desk.