We have a vendor that we prepay so they can purchase materials to build our product.  I have a situation where we prepaid the vendor in May of 2020.  Since then we have several bills from them that I have applied this payment to.  Only parts of these bills are paid with the prepayment and the rest is covered by check.  In March of 2021 I applied this payment to a bill.  Let's say I have prepaid the vendor $1,000 and the bill was $700 and I paid the whole $700 with the prepayment.  This brings the prepayment balance down to $300. Now I am finding out this was incorrect, and I was only supposed to apply $300 from the prepayment and the balance of $400 by check.  Because this was a prepayment and I paid this bill by going to Pay Bills and Set Credits, I cannot unapply the payment from the bill.  Does anyone know how to do this so that I show the $400 portion of the bill still open and the prepayment amount open for $700 ?  We use Desktop Enterprise.