Order completion page problem

The site is working fine when I go to place an order, the cart page comes up and it works fine, and as soon as it takes me to the order completion page, the Wood Mart logo appears, not my logo, and I don’t know where to edit it. The two pictures show how it works fine, and as soon as I go to complete the order and I go to this page, it crashes. I want to know where to edit it.