To print receipts, you need first to setup your printer in 'Settings/Printing/Printing tests'.

Before closing your sale, you can only print a proforma receipt (draft ticket).

When you close a sale, a receipt is automatically printed, with the closed sale number and the ticket signature (Sign).
The Sign line (Signature) is used to track the printed receipt (account, time, content...) as required by some legal authorities.
You cannot delete it or move it on the layout.

To print the ticket at the customer’s request, disable the right in 'Settings/Users/Access management': 'Print the receipt automatically when a sale is closed'.
In each closed sale, you can print a ticket with the 'Receipt' button.

You can also print a ticket on a PDF A4 paper.
To transform the ticket in an invoice, you must assign a customer to your sale WITH an invoice address.
Before closing your sale, you can only print a proforma ticket/invoice (draft invoice).

To configure the receipt layout go to 'Settings/Printing/Receipt'. More information.