Hi T-Man
With MYOB, there are 2 factors at play - purging of prior year data and current FY. Historically, all versions of MYOB allow you to generate financial statements for the current FY, the next FY and the previous FY.
This however will not show you a customer's sales history, as this is not included in financial statements. You would need to use a Sales Report (Customer) or the Find Transactions (Card) screen, neither of which are limited to a set time period.
If you cannot see the customer sales from 2018 in Find Transaction or in a Sales Report, the reason would be that this prior year data has been purged. This happens by default during the FY rollover process, unless you choose to override and 'Keep' Closed transactions. Purging is a process designed to keep the size of the MYOB file down as performance deteriorates as the file size gets larger. To view customer sales in 2018 you would need to restore a backup taken before this data was purged.
The current version of MYOB is AR2023, this does allow a user to generate financial statements for earlier FY's, provided the transaction data has not been purged (AR2023 does not have a purge function, however the data may have been purged before the v19 file was upgraded to AR2023).
As with v19, AR2023 will also allow you to view Customer Sales back to 2018 provided these have not been purged.
Hope this answers your question.
Regards
Gavin