Thank you for the reply. I did not find related answer in the readme.
At mouse hoover I see the enlarged image coming up for every image I have in my list, but I wanted to change the defult image size from 100x80 to 150x120 in the - Configuration > Images - section so it shows a little bigger when the visitor watches it without moving the mouse on it.
Once I try to change the dimension to even just one pixel and hoover over it, the enlarged image does not show up, IH4 no longer has function even if I hoover on an image that I left as defult 100x80.