Hi Lisa J
Thanks for the case description. When you use Teams on your desktop and receive a prompt to use an authenticator, it usually means that your organization has enabled multi-factor authentication (MFA). This is a security measure that requires you to provide a second form of authentication to protect your account from unauthorized users.
If you need to turn off MFA, please contact your administrator:
If you further need to turn off "Secure Default MFA", please refer to this reference (not recommended).
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