I'm assuming you are referring to how the report has an option to include the prior year but nothing beyond the year selected and the prior year.

If this is correct, you are probably best off using either a custom report, BI tool, or Excel to query the data from the AR_CustomerSalesHistory table.

https://help-sage100.na.sage.com/2019/FLOR/#File_Layouts/Accounts_Receivable/AR_CustomerSalesHistory.htm