There are a variety of customization options available for your receipts.
Under tools -> options from the invoice screen, you'll find a few of these:
Under the receipt tab, you can set the number of copies of receipts that print for credit card transactions and all other transactions.
Under the company information tab, you can set four lines at the top of the receipt that will appear. Most typically, it will be in the following format:
Company Name
Address Line 1
Address Line 2
Phone Number
The company name line is also used for printing barcode labels.
Under the couponing tab, you can set up to five lines that will appear in the box that appears solely on some USB Epson-compatible receipt printers.
Finally, from the invoice screen, by going to view -> general invoice notes you can set up to ten lines on each and every copy of every receipt.