1. Log into your Office account
2. Click on your User Name on top right of the screen  
3. Click View Account 
4. Click on Security Info 
5. Click on Change 
6. A Pop up appears with a drop down menu with your current preferred method listed.  
   Click the drop down menu 
7. Click on the new preferred MFA  
8. Click on Confirm 
9. A Pop up message appears briefly stating your method has been changed.  
10. Your default Sign in MFA is now changed.