It doesn’t change the Site Header background but allows you display the page / post featured image and you can merge it to sit behind the Site Header.
2. If this is still relevant after #1 then check the Customizer > Layout > Header – and i would guess you have the Mobile Header option checked which replaces the normal site header.
There was some misdirection on my part, regarding the first message I sent. I do not have
GeneratePress 2.1.4, but GeneratePress Premium 1.6.2 instead. So I do not have Elements to activate. Is there a way to accomplish the above goals apart from the Elements section, other than with complicated CSS? Elementor perhaps?