Closed invoices cannot be changed. An invoice can only be cancelled completely. With these two methods, you can still post the cancellation correctly:
Sell the product with a negative quantity
- Find the product being returned
- Add it to a new invoice
- Click on the product on the right side of the POS
- Click on the minus sign to put the quantity in the negative range
- Sell the product or add other products to the invoice
Cancel the entire invoice
- Find the entire original invoice in the admin area or on your POS
- Cancel the found invoice completely
Important: This method postpones the entire turnover to today and is especially suitable if the goods have been completely cancelled.