Nivo slider

Hello,

I have Nivo Slider in my new theme. It is working fine but I have one problem. One image from slider appears on my pages and categories. I tried to replace this image in slider but it still appears on pages and categories. It is annoying to see the same old image. I would like to replace it with new image if is it possible, I don´t know where to change image url. I found url of this slide only in style.css. I tried to replace it but nothing changed.

Next think I want to ask is it possible to add slider on all pages and categories?

This is the theme
http://www.templatemonster.com/wordpress-themes/38546.html

Thank you