Ok, I figured this out in case anyone is having an issue. When editing in a front end editor (in my case Woo360 builder) edit the row with the header image. Scroll down to background photo and you will see your image. Then select “small and medium screens” under Responsive Backgrounds and choose the same photo (or a new one if you want) from your image gallery and the appropriate size/compression. I chose large and it looks good on my phone but will depend on your image size. Once you’ve saved your new settings you should see the new image on your device.
I have no idea how this looks on other builders but it worked for me!
