Ahh, i see what you mean, on the 2nd screen... unfortunatly you cant change that its hard-coded, its just there to tell you that the 'source' is coming form the jukebox (when not playing a track).
As for the background image/s you can change them or even make your own theme with new buttons & backgrounds etc...
Make a copy of the 'Basic Blue' theme folder found here:- C:\Program Files\Pub Jukebox\System Images\Interface Images and then give the copied basic blue folder a new name like 'MyTheme' or something, then edit the images in the folder to suit your needs .
You will then be able to switch to your new theme in Pub Jukebox-> system admin -> Theme
Steve