Hello wpruitt,
Andrea here from Themes2go Customer Support and I’ll assist you with your request.
The setting you found in Customize -> Header is the default background image of your website.
In order to change the homepage header background, you should edit the page with Visual Composer, find the first row containing your hero titles and edit its background.

See this image as reference: http://d.pr/i/jd8vnD

If you have any other issues feel free to ask me.
Have a good day,

Andrea

I am sorry I got it wrong. I thought you need to edit the header image of the homepage instead of a single normal page.

In order to change the header background image of your page you need to edit it and add a featured image to the box positioned on the right bottom corner of the page

See this image as reference: https://d.pr/oMz2Nr

This should fix easily your issue.
Keep me posted on this.

Andrea

Glad this work for you.
If you need more support I am here to assist you.

All the best,
Andrea