It is recommended that you configure at least one other method. This will allow you to still MFA or reset your password when your primary method is not available.
Go to myaccount.microsoft.com and click "Update Info" under "Security info."
Click Add sign-in method
Click "Choose a method" and select the method you want to add and follow the instructions.
If you want to add a phone, continue following these steps.
Enter your phone number and pick method to receive a code.
Enter code that Microsoft sends and click Next