Hello caribman2020 !

If you have already the new menu and set within + you already set this menu as a submenu for the "About us" to then you need to edit the "About us" point via the following way:

1) add the javascript:void(); to the URL field's value;

2) add the "bx_menu_popup('[the submenu name]', this);" code to the Onclick field's value;

The submenu name can be known in the Studio->Developer->Navigation area.