I'm using K2 aspect of showcase my items. I've produced a food selection during my primary menu for showing my product groups (without sub groups) inside a catalog style (To get this done I visited- menu item> K2>Item Listing>Categories). I've produced three product groups and six product products, however when I click the menu I produced it simply shows just one category.

I wish to display all of the groups inside a catalog style (No sub groups or products) when clicked on around the menu. For instance: http://demo.getk2.org/en/catalog

Can you please kindly let me know how to get this done?

Thanks ahead of time

You have to set the parameters based on how K2 groups display in:

K2 > Categories > [Your Main Category] > Category View Options > Sub-category handling

(Alternation in the Parameters... you may also make use of the 'Inherit parameter options from category' to create other groups to follow along with exactly the same format when you have it setup the way you want)