Hello Chen Bin,
Thanks for your question.
If you did not backup your existing Authenticator you will need to contact your IT admins for the work/school accounts with issues for assistance.
However if you have access to the old phone follow the steps below:
To move your authenticator app and configure accounts without losing data, you need to:
- Go to your authenticator app
- Open Microsoft Authenticator. Tap the three vertical dots at the top right, and then tap "Settings."
- In the "Backup" section, toggle-On "Cloud Backup" on an Android phone, or "iCloud Backup" on an iPhone.
- This will proceed to back up your data. (Note, this will back this up to the account you used to set authenticator up)
You can then proceed to navigate to your new phone
- Open your fresh Authenticator and navigate to recovery tool. In recovery you should see >> "Already have a back up? sign in to your recovery account"
- Once you do this, You'll be asked to sign in to the Microsoft account you used for the backup on your old phone. Your accounts will then automatically be added to Microsoft Authenticator on your new one.
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Regards,
Abiola