Credit notes

A customer over pays the invoice by R90 and merely wants their account credited - no goods returned as these are correct and no physical refund.
I have filled in the credit note customer details etc .When i open account to be allocated it merely gives me sale and expense accounts and i am lost where to allocate it.Out of interest i did not allocate it to any account and obviously it went into the suspense account however the customer balance doubles from the original over payment of R90 to R180,. If i enter the sum as -R90 is reflects a nil balance on the customer account.
i know i am doing some thing silly,and have read the guides but i am clueless - more so as this is a small business and i am not clued up on these matters
Thank you

This is exactly what you should have expected. The customer’s original overpayment created a credit in Accounts receivable of R90. By issuing a credit note, you reduced the amount they owed by R90. So their account now stands at a credit balance of R180.

Credit notes are not used to reverse overpayments. They are used to reduce amounts owed to you by the customer.

What you should do is go back to the receipt where you recorded the customer’s incoming payment. Break it into two lines. Allocate the first to Accounts receivable > Customer > Invoice and make the amount match the original balance due of the sales invoice. (If you generated the new receipt from the sales invoice, this would be the default.) This will fully pay the invoice and cure the overpayment.

Allocate the second line to Accounts receivable > Customer, but leave the invoice field blank. The credit will be available and automatically applied to the unpaid invoice (if any) from that customer with the oldest due date. If no other unpaid invoice exists, it will be applied to the next one you create.

Delete the credit note.

Thank you very much for the assistance,the older I get the blonder I get but the more I learn