The category drop down will automatically show all categories. You can use enable_category_by_root_parent option to limit which categories are shown in the drop down by limiting the drop down to specific root parent categories [see definition of root parent category]. This is very useful if you want to create multiple directories. For example on a chamber of commerce site you could show a directory business members on one page and on another page a directory chamber officers with all entries managed by a single installation of Connections.
DEFINITION: root parent category – This is a category that is not a child of another category.
NOTE: This option must be use with the category shortcode option.
Get the demo shortcode
[connections category=31 enable_category_by_root_parent=true]
The category drop down is not being limited to a root parent category.