Instructions on how to use this

how do you use this plugin? i installed it and looked at options but how do get it to work on my menu items?? look at https://jimb101.staging.wpengine.com/portfolio_page/sulfur-hexafluoride-sf6 and menu item ‘products and services/Electronic Specialty Gases and Chemicals’ and you will see sub menu of about 20 items. There are about 20 more that don’t show up because the menu is not scrollable.

The page I need help with: [log in to see the link]