If your credit card is somehow accessed from a place very far from where you normally reside, the card company will send you a message as an alert. This is good for the customer and the company as it hopefully reduces the level of fraud.
If because of system weaknesses your log in details are obtained and an unauthorised log in is achieved using the details of an authorised user, MYOB should like the credit card company be able to monitor the access of each user and if I live in Perth and suddenly there are several log ins from the USA, a simple message alert from MYOB could assist in minimizing any damage from this fraudulent activity. If as the Accountant or Bookkeeper you have access to the MYOB data files of say 50 clients the unauthosied use of your log in details can see every one of these clients being breached. If you dont know its happening how can you do anything about it.
To assist your own situation please use the the two factor authentication security that is now available and MYOB you need to treat all MYOB users like they were users of a single company so increase your monitoring of all client log ins and report suspicious access when it happens or build it into your software so users can self monitor. The current system log report you can run is inadequate as all it does is show the log ins of existing authorised users but it doesnt show from where the log in is made, so unless the log in occurs at say 3 am how do you know from looking at the report that the log in is not authorised, given that the majority of unauthorised log ins will occur due to compromised log in details of existing users.