When you click the gear to view the row options for a hero section, and click the style tab, and scroll down to "enable background options" if a background is already set no option in enbale background options is selected so its hard for someone new to work out where the existing background image is being set from until you click "Image" and then you see it, and the styling is applied the the "Image" button option to show it is chosen.
what it looks like 
what it should look like 

