Hi there,

This is a customization question and support doesn't offer customization services as we wrote on our support homepage and on this area. I will try to help you this time though

I can see that you already did that. So to apply that change you should add a CSS code like this:

header.site-header ul.nav>li:hover>a, header.site-header div.nav>ul>li:hover>a {
    color: red !important;
}

Will set this ticket as solved from here.