Once an order is closed at the Sales Point, it becomes a fiscalised invoice with a unique number and signature — its content can no longer be edited. What you can still do on the Sales Point is print an additional copy or void the invoice in a separate, fiscally recorded operation.
Both actions are reached via Menu → Invoices.
In this section
Voids and invoice copies are printed on the same receipt printer with the same template as the original invoice — see Printer settings.