Can’t find where to modify header images

Hi everyone,

I am working on updating a site I didn’t originally design, and there is a lot to the setup that I am not familiar with. I’d like to change the three current images in the header on the homepage, but I cannot for the life of me find where they are defined in WordPress. I’ve tried customizing the theme, but the option isn’t there. I can see from Inspecting in Chrome that the slides are in <div class=”slides”>, and I can see in the header .php file where the slides get pulled in. There is also a plugin called “Custom Fields” that looks promising, but I’m still not finding where the three images are set.

The site is http://www.singlesrc.com/ – thank you in advance.