Magento: JM Products Slider

On my slider(JM Products Slider) the “Number of Element” is 4 on the row and the “Qty of products” is 20. when I click on the “previous” or “next” buttons, it just shift one product I want to shift all the four products!!! How can I do that????

by changing this code:
scroll: 1,
scroll: 4,
in /skin/frontend/default/default/joomlart/jmproductsslider/js/jcarousellite_1.0.1_custom.js