Aeon Nox SILVO theme background problem

Hi guys so im trying to add multiple custom backgrounds for my build. I am having problems where when I go to select multi or single backgrounds it doesen’t give me the option to choose from my computer files only from the kodi sources.

http://imgur.com/a/Haziw 2 images here.

It won’t let me go through my computers files when i try to use multiple custom photos or single.. Any Ideas?