I'm having some trouble changing the desktop background for my external monitor on windows 8.1. For setting the background on just my laptop, I can right click the picture and hit Set as desktop background, which works OK for that background, but doesn't work for my external.
When I go to the personalization settings, if I try to set a new background for my external monitor (by going to the wallpaper settings, right clicking on the image and hitting Use for monitor 2) or if I try to use one of my pre-existing themes, it changes correctly and everything looks fine until I close the window, at which point any changes I made go away and the background on both monitors reverts to solid black.
Once I've opened the personalization settings and changed the theme (to one of my custom ones, the built-in themes don't have this problem) the only way to get the background to display (without leaving the personalization window open) is to reboot the computer.
I know my copy of Windows is activated, I'm not in high contrast mode, and I've seen the techniques people have suggested here, but none of these have worked for me, especially having an extra monitor and all. Does anyone know if there's some sort of registry hack to stop this annoying behavior?