Hui @ALeinweber,
do you mean dropdowns like the “About” menu item in this screenshot?
If so, you can set this in the global navigation settings by drag&drop the menu items that you’d like to have as dropdown items onto/below the desired nav item. You’ll find the navigation settings here:
Hub settings(gear icon top right) → Content → Navigation menus → YOUR MENU
Once created open your global header and select the desired menu. Save/Update/Publish → done
best,
Anton