My header image doesn't display in thesis 1.8

I am editing a WP site that was developed by someone else. I wanted to replace the header image with another one. I uploaded the image under the Header Image tab but it did not replace the old one. The new one is still displayed in the Header Image section. I looked for css and php code that might give instructions about the old header so I could replace that, but found nothing.

In the header display options I unchecked “show site name in header” and suddenly NO header image displays. I read a post indicating that “show site name in header” should be checked so I checked it again but still no header image displays. Although I’ve developed a number of websites I’m new to WordPress. I don’t know what to do next. Not sure if I’m using WP version 3.2 or an earlier version. The website is https://www.thesmithconnection.com