If ClassLink keeps choosing a personal Microsoft account, your browser is probably already signed in to that account.
Fix the account selection
- Go to myaccount.microsoft.com.
- Select your profile picture or initials in the top-right corner.
- Sign out of the personal account.
- Sign in with your school account.
- Return to ClassLink and try again.
If it still happens
Try a different browser, or ask your form tutor to request IT help with clearing the browser sign-in state.