Currently, there is no such option available to show the remaining outstanding amount on the payment receipt once you receive the partial amount of the total amount pending from the customer.
But we do have the show the total payable amount on the invoice if show net balance is turned on from the document settings.
Alternatively, we can suggest you please share the ledger PDF with your customers so that they can see their total pending amount.
To show the Net Balance on invoice PDFs,
Please go to Sales>>Invoices>>Document Settings>>Show Net Balance>>Turn ON>>Save and Update.
To share Customer ledger,
Please go to Customers>>Select Customer>>Ledger>>View/Share Ledger.
