Auto fill Description field

i thing it is very good wen we are using receive money in invoice view auto fill Description field with invoice #
because in cash accounts it is coming on list
thank you

That isn’t the purpose of the description field. The purpose is to summarize the transaction. Further, you are apparently using sales invoices for counter sales, which is unnecessary. Sales invoices are meant for sales on credit.

Following your workflow, however, the documentation provided to a customer would be a copy of the sales invoice showing the amount credited and the zero (or at least reduced) balance due. Why would you want the invoice number in the description field when it is already on the face of the invoice?