I know there are extensions to modify the PDF invoices and packing lists. I'm assuming by PDF invoice, they mean the invoices that you can print from the order summary in the admin. However, when a customer goes to their account page in the Magento store they are provided with a link to a HTML version of the invoice. The customer's HTML invoice and the admin's PDF invoice look very different. My question is, where is the template or file located that I can customize the HTML invoice that the customer sees?
Or is there an extension to be able to customize the HTML invoice? I see a ton of extensions for modifying the PDF invoice, but I'd really like to modify the HTML invoice which is what the customer sees.