Sage 100

Hello all, A customer overpaid on a check for three invoices. They want to short pay a future invoice due to this. How can we create a credit to apply to a future short paid invoice? Thanks! D.

I'm a new user of Sage 100 ERP 2013 (v 5.00.8.0) and am trying to post cash receipts. I have a client using three checks to pay one invoice. I entered the first check fine, but when I try to enter the second check and apply it to the same invoice it says…