Reply To: Add Top Categories to main navigation

>>You need to switch to the Edit menu tab. https://www.wpbeginner.com/beginners-guide/how-to-add-navigation-menu-in-wordpress-beginners-guide/
I have already created the menu & I understand to set it as the main site navigation, one can tick Main menu below the menu editor.
My question is on your theme, where exactly have you set Main navigation as the main (primary) menu.
Thanks..