You can select from within the ClassiPress admin dashboard how many child categories you wish to have appear on the dropdown menu and/or homepage menu as shown here on the
ClassiPress admin dashboard demo For the dropdown menu you set the "Categories Menu Item Options" > Category Depth > Number of Sub-Categories and the main page category box is "Categories Page Options". So you can simply "Show All" or "0" if you don't want a pre-determined number.
The ClassiPress theme you get out of the box is what you see on the
AppThemes demo site as "ClassiPress", and
all other child themes are separate purchases from the
AppThemes marketplace here, including the "Flannel" child theme which also is a separate purchase (Unless you are purchasing the AppThemes Club Package). Please note that you must purchase the ClassiPress theme in order to use any of the child themes. Thanks.