I can’t find where I can determine when the menu will show the second section when I scroll down.
This is because you haven’t added a menu that having a link(internal link) to #intro-slogan section yet.
I’ve also found another problem. I’ve changed the skin colour and it seems to keep appearing the orange one when I change the hover to another part of the menu.
You can use the below custom CSS in themeoptions –
#primary-menu > ul.menu > li > ul.sub-menu {
border-top: 3px solid #078439;
}