Error message "Another account from your organisation is already signed in on this device. Try again with a different account."

Hi @Matthew Crawford

As Office for iOS are not supported on Q&A, to help you better, it's recommended to post a new thread on Microsoft Answers community.

I personally suggest you close all Office apps on your iPhone.

Then go to Settings > Select Word/Excel or other Office apps > Under RESET, tap Reset 'app name' > Enable Delete Login Credentials > Restart the Office app and try to sign in.

Hope the information could be helpful.

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