Apart from above request, could you share the screenshots of the configurations made at your end for the menubar. Is it like create link configured in pyPortalHeader section? In Pega 7.2.2, while launching the CaseManager portal and user hovers over this link and menu items are shown. While the menuitems are hovered, then the change of color is observed.
Menus style can be modified easily in the application skin. "Active Text", "Active Description Text", "Active Background" and "Active Border" in the Menu Bar tab of Menus component in Skin, might be the one you're looking for.
Else inspect the Menus and give your own styles on Hover, by using the classes that get generated for Menus on Hover.
Please check the two screenshots attached which might help.