By default the Total theme uses a CSS hover for the header menu dropdowns. This means when you hover on a parent menu item the sub-menus will display. Via the Customizer you can change the default behaviour if you prefer items open on click instead of hover or if you rather use the older “SuperFish” script which uses javascript instead of pure CSS.
Go to Appearance > Customize > Header > Menu Dropdowns to locate the Dropdown Method setting which looks like this:
