The following setting is found on the
Look and Feel Settings -> Header, Side Panel and Welcome screen.
Built-In Categories: This field allows you to define a list of "built-in" categories, which means the categories and their products are available for display on any page of that application. You may enter a comma-separated list of containing the values of the categories' code fields to define the built-in categories.
When you update the Built-In Categories setting, it does not automatically reload the built-in categories you enter. To trigger a reload, simply navigate to the Details screen for one of the categories and save the details without making changes.