Drop down menu option

Hello! I downloaded this theme yesterday to make a child theme for my portfolio. The default main navigation bar gave me the option to have a drop down for a page that had sub-pages, which was totally awesome. I went ahead and updated the nav bar to have a home option instead of the sample page, and when I saved it, the drop down capability went away. I tried activating a plugin for a drop down, but I can’t quite figure out how to make that work on the site. All of that said, is there a way to get my drop down back?? It’s not a huge deal but I thought it would be a nice (albeit small) feature to have. Thanks!