If you attend multiples schools that use Office 365, you will need to pay attention to which Office 365 account you are signed into when interacting with each school.
Switching Between Office 365 Accounts
If you find yourself signed into the wrong Office 365 account, you can sign out of your account or sign into another account by clicking on the icon with your picture or initials in the top-right corner of the browser Window.
Using a Separate Brower for Each Institution
Another strategy is to use a different browser for each institution. For example, if the browser you normally use is Chrome, you might want to use Chrome for your primary school and Microsoft Edge for your secondary school.
Creating Browser Profiles for Each School
Google Chrome and Microsoft Edge both support the creation of profiles, which keep browser data separate. In Chrome, click on the circle in the top corner where your initials or picture is and select "Add" under profiles to add a new browser profile.