Microsoft 365: Add or Re-Add Authenticator App for MFA

Authenticator is the recomended method for Multi Factor Authentication (MFA.) You may need to add or re-add this as an option for any number of reasons including:

initial setup
changed phone
administration requirement
troubleshooting

Visit office.com and click sign in top right of the page
Use email address as the as the sign in and use your same password you sign in to get into your computer - NOTE: if your email address doesn't work try using different accounts you've used for other sign ins. Contact IT if you have further questions.
Once here, click your name on the top right, it will bring down a sub menu and click on "View Account"
After clicking "view account" it will open a new tab/window and you will need to click "Update Info"
Here it will bring you to the "Security info" tab, here you need to click "+ Add sign-in method" a popup will appear -> click "Choose Method" -> choose "Authenticator app"
Go through the prompts and follow the instructions step 6 is different so please read step 6.
Here is where it is a little different, it states you need to add a "Work or School" account, DO NOT do that, you should press the plus button "+" on top right of the Mobile App and select the "Other" option.
After selecting other it should prompt to scan a QR code. Scan it and follow the rest of the steps.

You are done and have added an authenticator app option to your account.