I have my laptop attached to my monitor and my background is set to display the same image on both monitors. The image is the same resolution as the external monitor (1920x1080) and sizing is set to "fit width and maintain aspect ratio". When I have the monitor plugged in both screens have a properly sized image but, once I unplug the monitor and I am only running on my laptop (1366x76 the wallpaper stays at 1920x1080 instead of re-sizing to fit the smaller screen. I have to then go into the wallpaper settings and click "apply" and the the wallpaper is properly sized.

How do I get it to change the settings automatically whenever I plugin or unplug my external monitor? This is the only thing stopping me from upgrading my demo version to Pro.

Sorry I just solved my own problem. I created two monitor profiles and two desktop profiles. One desktop profile was set up for dual monitors and the other for laptop only. I set each of these profiles to the corresponding monitor profile.