Please help! Pages' feature images started to replace the header!

Hello everyone!
We have recently updated our theme ZeeDynamic and since then we’ve noticed that the pages’ featured images started replacing the customary header image with our logo. It only happens to pages, not posts, and we think it’s related with the theme upgrade.

The main header of our blog should be one of these three images (they rotate randomly):
1) http://hitchhikershandbook.com/wp-content/uploads/2013/11/cropped-Header-4-1500.jpg
2) http://hitchhikershandbook.com/wp-content/uploads/2013/11/cropped-BH-2-1500.jpg
3) http://hitchhikershandbook.com/wp-content/uploads/2013/11/cropped-Header-1500.jpg

But if you click for example on “Jon” page (http://hitchhikershandbook.com/about/jon/), the header image is replaced with the page’s featured image, which in this case is Jon’s massive face.

We don’t want the pages’ images replace the header image of our blog!

We looked into the code but we are no experts and we’d really appreciate if somebody gave us a hint how to change it and bring it back to what it was. We also posted a similar question in the “Themes” section of this support forum but were left without an answer.

Thanks a lot for all your help!
Our blog is:
http://hitchhikershandbook.com/