If you are about to change the device that you use for Multi factor authentication (MFA), you must take one of the following two actions.
(1) Remove MFA from your MX account and then go through the setup process again or
(2) Ensure all of your accounts are backed up inside the authenticator app (this is not available with all apps).
If you fail to follow either of the steps above, your MX account will still be linked to the old device and you will be locked out of your account. You can still use your password and a backup code to access MX and then follow the steps below.
Instructions
Go to Settings => Account Information
Click 'Change Multi-factor Authentication Settings'
Alternatively, the link below will take you directly to this page if you are logged in to MX.
https://access.mymxdata.com/faces/account/profile/multi-factor-authentication
Once on this page, click 'Remove Multi-Factor Authentication'.
If you fail to save your backup code (or run out), you will need to speak to your MX administrator regarding a MFA reset on your account.