How do I choose authenticator account?

Question

I have both a school and work office 365 account. I am trying to use the Microsoft app on iPhone, however, when I click on the file I would like to open it wants me to enter my two factor authentication in the Authenticator app. When it auto loads the app it opens the wrong account. My only option is to either cancel or login. If I cancel it rejects the authentication and will not allow me to open the file. If I choose to login, I get an error saying, “ AADSTS90072: User account 'MY SCHOOL ACCOUNT' from identity provider 'MY WORK PROVIDER' does not exist in tenant 'MY WORK' and cannot access the application ‘…’(Microsoft Office) in that tenant. The account needs to be added as an external user in the tenant first. Sign out and sign in again with a different Azure Active Directory user account.” I know that my school account cannot be found on my works database, but I don’t have any options to authenticate via my work.