When listing an item for sale; an option is given called 'List in'

It directly affects how the item you have listed can be searched.

There are 3 options - Site, Store or Both, defined below.

Site:   Anyone can search it from the Homepage

Store:   Can ONLY be searched for within your store

Both:   Can be searched for from the Homepage

We recommend - you use the setting 'Both' for maximum visibility.