Background Image Won't Change in 'Customize'

I’m just trying to change my background using ‘customize’, nothing fancy. It seems to be stuck on “saving changes” and never changes the actual blog. Although when I go back in to ‘customize’ it uses the background image I’m trying to change it to, not the current live image the site has.

Blog: heartbeathappiness.com
Theme: Forever
Current live image: An alex grey painting, lots of veins and purple pink color, though you can barely make out what the image is.
Image desired: Rave Crowd
But really, I just want an image that is more in line with the content but it just will not happen for me ??

Any ideas?