Take a look at section 35 in the user manual ("Exporting Data"). You'll want to modify the "Receipt.html" file that is in the "templates" folder. Better yet, make a copy if it and edit the copy. On the Preferences tab, select the "Receipts" category, and change the "Generic template" to point to your copied Receipts.html file. This way you always have the original, and your edited version won't get written over if you update the software.
Section 35.11 lists the tokens you can place in the Receipts.html file. The ones you're interested in are <tablename>, <seatnumber>, and <seat>.