If you previously selected the Authenticator App method and then switched to Email or turned off the feature, your old account in the app will still exist, but will not work with MySonicWall anymore. In this case, you may want to remove the old account from the app:
1. Launch the Authenticator app.
2. Hold your finger on the old MySonicWall account until the option menu pops up.
3. Tap Remove.