Reallocate a receipt against a client invoice
On the main menu, select Bookkeeping > Cash Posting > Sales Ledger Receipts.
On the Client > Assignment window, click Sales Ledger.
In the Sales Ledger window, ensure that the Show Zero check box is selected.
Select the receipt that was incorrectly allocated.
Hold down the [Ctrl] key and select the invoice to which the allocation was made.
Both the invoice and the incorrect receipt should now be highlighted.
The correct invoice is now paid and the incorrect invoice is now unpaid.