To specify the privilege level required to override an alert:
If the user's privilege level is equal to or greater than the one specified here then he/she can override the alert and continue with the transaction.
If the user's privilege level is less than the one specified here then he/she cannot continue with the transaction. To override the alert, you can click the Supervisor button and then a user with a high enough privilege level can login to continue. We then automatically revert back to the original user.