Outlook O365
Using a shared computer
Prevent Single Sign On and auto-MFA from allowing someone else to access your e-mail.

The issue:

On any computer.  Once you have logged into your Outlook or Teams local client your Outlook and Teams clients will not ask you to sign in gain.  They will simply open using the last set of authorized credentials.

If you have multiple people using the same computer – using a generic login – this poses an issue where the new person will log in, launch Teams or Outlook and it will automatically sign them in as the previous person.

EVEN if the previous person as Exited or Quit the Outlook or Teams application.

The Fix:

You have 2 options:

1. If the user logs into the computer with unique credentials this issue will not occur.

2. If you absolutely must have generic credentials to access the computer, the users should NOT be using installed local O365 applications.  Use the web apps instead
office.com
Log in using your unique Active Directory credentials.
When you are done, Sign Out.