However, there may be cases in which this scenario is not detected and the Microsoft 365 user interface may show that another user is successfully signed in. Microsoft 365 makes a best effort to prevent a second user from signing in when another user from the same organization is already signed in. However, Microsoft 365 only supports one Microsoft 365 user sign-in from each tenant or organization per session. If you have multiple Microsoft 365 user IDs from different organizations, you can access content from the SharePoint Online deployments of each organization.

In Microsoft 365 apps, you can access Microsoft 365 content in SharePoint Online by providing your Microsoft 365 user ID and password. Sign back in to the Microsoft 365 application.

In this example, user is already logged in, but you are trying to login as user the top right-hand corner of a Microsoft 365 app (Word, Excel), select your name, and then select Switch Account.

Sign out of any Microsoft 365 accounts that are signed in.

The account you want to use to edit the document with the Microsoft 365 desktop app (Word/Excel etc) needs to match the account you are using in FYI. It occurs if you are trying to sign in using a Microsoft 365 account that is from the same organization as a Microsoft 365 account that is already logged into Office on the same computer. 'Sorry, another account from your organization is already signed in on this computer.'

When signing in to a Microsoft 365 desktop app (such as Word or Excel) using your Microsoft 365 user ID and password, you receive the error message:

Microsoft onedrive sign in issues