Can Desktop Slideshow be disabled?

Today I changed wallpaper by ticking an image. (What i did not know, was that another image was also ticked, so suddenly I had a two image slideshow) Now, whenever I open personalisation to change wallpaper it is ticking all images by default, so that I have to clear them, and then select the single wallpaper I want.

Previously I was selecting wallpaper by clicking on the background image below the window, and it would simply change that single wallpaper. Now it initially selects all images in a folder.

My other win7 PCs don't do this "select all"

It's like do it once and it becomes the default behaviour.

Personally, I do not want a background wallpaper slideshow. I searched Google. I failed to find a way to turn this default slideshow selection off by any other means than "clear all".

I realise I may be the only person on Earth bothered by this insignificant nano-problem, but does anyone know how I could either revert the default selection to cleared, or disable the wallpaper slideshow option.... permanently?

Well, at least that stopped the "all ticked" behaviour.
If it had not been for this I might never have noticed there was no obvious way to do this.

Thank you Stephanie.