I have tried other themes with visual composer bundled, and I can see the a field call “custom row id” under “row settings” (please see attachments)..
But your version of visual composer do not have that.
Alternatively, you can tell me how to achieve this. I have a one-page site, I want to be able to scroll to each section (anchor) of the page when user click the respective title on the top menu bar.
For example, my top bar has Home | Product | About Us | Contact Us
When user click about us, the page will scroll to About Us section (or #aboutus)