Select menu's hierarchy show I would like it to show the hierarchy of menu's links. Testimonials and Company are under About us. How can I achieve this effect? Let me specify with an image:
You just need to make the About us as Expanded and place the menu items Testimonials, Company under the About us. Please see the attached screenshots  





Here, About us acts as parent item of Testimonials and Company.
After that just need to add and set the css in style.css file to the menu to be displayed accordingly.

Hope it works for you!