Hopefully this will help some poor soul out there. In order to solve the problem of Authenticator App showing 8 digits and need 6 digits for login, I had to delete the account from my authenticator app and then re-add it. In order to do this you first have to turn of sync account in the authenticator app. Go into the authenticator app on your iPhone, click on the three bars at the top left and go to settings, scroll down to sync account and Stop Sync and Remove Autofill info.
Then go to authenticator app main page and click the account you want to remove. Click the gear at the top right and then "Remove Account".
Next you need to re-add the account to authenticator. For my MS 360 account I had to go to https://myaccount.microsoft.com/ and log in. Select Security info on the left, then remove the MS Authenticator by clicking the Delete link. Then re-add it by clicking the Add sign-in method at the top of the list. This will take you through the process of creating a QR code you can scan on your phone to re-add the account to Authenticator app.
Hope this helps.