At first, my question was why I had to crop my wallpaper wider than it seemed to be, but I saw that that question was already asked and answered here: Setting wallpaper - wrong orientation
So now my question is, if wallpaper is cropped wide so that it can scroll when you switch between screens, how come mine doesn't move? I am using a picture I downloaded from the internet on my phone, and as far as I can tell it doesn't move at all no matter what I do.
If it matters, my phone is a Motorola Atrix HD.
The launcher application on some phones does not provide the ability for a scrolling wallpaper, the only way to fix this would be to download a separate launcher.
Here is a list of most of them -
Citation: "Scrolling wallpapers glitch when they have infinite scrolling. If you scroll past the end of the wall paper, it'll sharply shift to the other side of the image. I would imagine some find this to be unsightly. The developers at Samsung probably see this as a problem and probably thought infinite scrolling was a more important feature than wallpaper scrolling."
In your Settings click the following: -Display -Home screen -Swipe effect -Panorama
DONE. Took me a while to figure this out on my own.