I just installed this too so it will aide in loading pages faster and could not get the little pop up image (when hovering) to apply in all images. it would only apply to the small image.

I finally got all images to have the hover image by setting them all to the same size....i set them to be width: 155 and height: 155 mainly because i did not want the images to be too large for more to show on pages

the controls for setting the image size are under configuration/images at the bottom of the list

and then you should see a pink "i" in the categories listing of your products to add the images in and there is another section under tools to look at or add images or edit the ones you uploaded.

you enter your descrition and information as usual then do your attributes then finally do the images and to do that you hit the new image button from the products "i" window then brouse your computer to where it is and click save....i entered mine into the small section and t took care of the med/lrg by itself.

very easy to use.

the load of info is for another noobie that may happen upon this thread.