Hello Matteo, 

do you want to change the navigation slider only for a slider (the one from the screenshot and which i found in the homepage) or for all the sliders of the same type?

Hello Matteo, changing the color for a specific slider becomes complicated. I don't have a solution handy right now.

For all sliders with white cursor setting plz find the following to add in customizer -> additional CSS with red color code as reference (you can change to any color you want)

.drag-cursor-white #ball {

    border-color: red!important

}

.drag-cursor-white #ball-drag-x:before, .drag-cursor-white #ball-drag-x:after {

      color: red;
}

.light-cursor .swiper-pagination-bullet .solid-fill {
     fill: red !important;
}

.light-cursor .swiper-pagination-bullet .path {
    stroke: red !important;
}