1. Theme settings can be reset in Dashboard > Appearance > GeneratePress
2. Delete any CSS imported by the Prime Site in Customizer > Additional CSS
3. Delete any Elements ( Appearance > Elements ) and Pages/Posts imported by the Prime Site.
I reset the customizer and then reinstalled the theme but it did not solve my problem.
The problem is on mobile.
1/ The search bar does not fit on the screen at the top by the logo – it goes off to the right
2/ When you scroll on the page about 1/8th of the way from the bottom of the page there is a line on the screen.