Looking to access your theme's code or language options with Shopify's new theme editor layout?
In your Shopify admin click on Online store > Themes
Next to the theme that you want to edit click on the Menu button which is a small square with 3 blue dots
This will open a submenu of options which includes: Edit HTMl / CSS and Edit Language
This Mega Dropdown needs a parent link assigning to it in order to appear when that link is hovered.
As standard we have assigned this to the Catalog link which is a default in all new Shopify stores.
If you would like to change this to show when a different link is hovered simply add the name of that link Exactly as you have entered it within the main menu link list
If your Main Menu contains a link typed as: Shop Now and this will trigger the mega dropdown simply type Shop Now into the field within the customise theme > Navigation section.
From your Online Store > Navigation > Main Menu Link list
Make note of the name of the link and the Case it is typed in as... For the Example we are choosing: Explore
In Themes > customise theme > Navigation Re-Type the Link title into the Mega Dropdown Link Text box.
Click Save and then test the link on your Store Front.
For further illustration please see this video