I closed the survey after opening it for testing, and I would like to change the header to an image from a solid color. I can select the image and it appears in the header pop-out menu, but there is no option to “Apply Changes” as there is if I simply change the color. The header image is a 750×200 jpeg.
Is this survey perhaps a copy of a previous survey? My thought is that if that is the case, perhaps the previous survey had a custom theme that may have some hard-coded styling?
Sorry for your trouble!