Hi EmilyC,
To make it simple to spot your sales transactions, you can customise the prefix and numbering sequence for your invoices, quotes, and sales orders within MYOB. Now, about the file naming by default, invoices generated from MYOB desktop will have the prefix "INV", while those from MYOB online include "INV-". There’s no built-in option to remove these prefixes automatically at the moment, so they’d need to be manually adjusted after the file is created. You may check this link regarding this. If you still need a hand, get in touch with our chat team through our virtual assistant MOCA or drop us a support ticket via MyAccount.
Regards,
Shella