How to change a header in a posts page?

Hello! I am using a custom header on a home page and simple header for other pages. In customizer I marked this page as "posts page". So theme answered by this design: http://test2.bonart.gallery/mdm-secrets/ 1. How to change entry-title "Archives"? 2. How to turn off a custom header for this page? 3. Where is located php or html file, which defines classes and other content for this page? Because page that I created in wordpress panel after marked as "posts page" does not influence on design. Please explain me where to edit this page now.