Accounts in Office
With most new versions of Office, you have an account that's associated with your copy of Office. This can be a Microsoft account, or work or school account. You use this account to sign in to your account portal where you can install or reinstall Office, manage your account and security settings, and access any files you saved to a cloud-service such as OneDrive.
Select from below what you want help with.
Where and how to sign in
Sign in to Office apps
How sign in works in Office 365
Switch between accounts