Option 1.

https://support.microsoft.com/en-us/account-billing/set-up-the-microsoft-authenticator-app-as-your-verification-method-33452159-6af9-438f-8f82-63ce94cf3d29

1. Sign in to your work or school account and then go to your My Account portal.
2. Select Security info in the left menu or by using the link in the Security info pane. If you have already registered, you’ll be prompted for two-factor verification. Then, select Add method in the Security info pane.
3. On the Add a method page, select Authenticator app from the list, and then select Add.
4. the rest of the steps are easy.

Option 2

1. Sign into portal.azure.com as the administrator.
2. On the left, select the menu button on the top left and then select Azure Active Directory from the drop-down list.
3. On the left, select users.
4. Select the user account for which you wish to re-acquire the QR Code.
5. Scroll down to Authentication Contact Info and select Authentication Methods.
6. Under Authentication Contact Info, select Access Panel Profile.
7. On the right, select Additional Security Verification.
8. You can now select Set up Authenticator App. This brings up the QR Code.
9. On the MS Authenticator app, select the user account for which you wish to re-scan the code and scan the code.