Thanks for your message. The reason you cannot see the head background picture repeated in all pages is that it has been removed from the template. In the latest version of Trivia that feature was replaced with a page title widget. We have just updated the sample site (http://trivia.basekit.com/ )
We have uploaded a custom Trivia template for you that works as the original version so you can have the same image repeated in all pages as in the original version.
If you check your site in the editor you will be able to see the change and, if you are happy with it, just need to re-publish the site.