Set global header
Set your header as the global header for your entire website
Once you have defined the styles you want, you just have to go to the page with the layout you imported, on this page you will find the different styles of top header and bottom header. First if you have defined a top header style, copy the corresponding style on the page then go to the back office, in Divi >> Theme Builder >> Edit Global Header and paste the section you just copied. Then do the same process with the bottom header that you will copy below the top header.