Hi there,
the Site Header has been disabled. Go to Appearance > Elements and look for the Layout Element where the Site Header has been disabled and delete that Element. This will give you the site header back.
The read more uses the colors set in Customizer > Colors > Button.
The back to top button used the colors set in Customiser > Colors > Footer –> Back to Top
To change the sidebar top widget color go to Customizer > Additional CSS and edit this:
.sidebar .widget:first-child {
background-color: #e86000; /* Change this color */
color: #fff;
}