To change that style, we would need to add a style of equal specificity that falls later in the CSS or a style of greater specificity.
(Do you understand “specificity”? If not, please read: http://reference.sitepoint.com/css/specificity )
To accomplish that, we will change the color with this:
.navtwo li.current-menu-item a {
color: #f26122;
}
This has greater specificity and falls later in the CSS, too.