@Joshua Lane Customization > Forms > Transaction Forms. Edit your preferred packing slip form (I'm assuming you're talking about the packing slip here, that's what prints by default when you print an item fulfillment). Look at the 'Printing Type'. If you've selected Advanced, go edit the relevant Print Template and Email Template in your Advanced PDF/HTML forms. If you've selected Basic, select your fields in the Header, Footer, Body, and Columns area in the sublists below.