About the header of page, we provide two ways to setup logo and other info.
1. From General Setting, Header Setting on our theme panel setting
2. From Page Setting when you edit/add a page - This panel will help you in case you want to set other logo for that page.
So, when you try to set logo on General Setting but it does not change, let go to edit that page and check the page setting, i think you can find the old logo in there.
Hope that will help.