How do I add/bring back the "ship via" field on my invoices?

Now that Quickbooks has forced me to use the new invoice interface, the "ship via" field is missing from my custom invoice template. When I open a new invoice and click "customization" --> custom fields "manage" --> it says "you don't have any custom fields" and the green "add field" button is faded out so I cannot click on it. The "ship via" column still shows up when I run my standard custom report (but of course all of the rows in that column are blank).

Thanks!