Download and install Microsoft Authenticator from the App Store or Google Play
Open the app and allow the required permissions
Sign in with your Microsoft account if prompted
Add an account by tapping the plus icon
Choose the account type you want to add
Scan the QR code or enter the setup key provided by the service
Approve sign-in requests directly from the app
Use the one-time verification code shown in the app when needed
Back up your accounts in the app settings
Keep the app updated
Use the app to manage passwordless sign-in if enabled
Remove old or unused accounts from the app when necessary