Filter by child category without having to also check parent category

See here: https://www.newageindustrial.com/resources/?p_asid=3&p_asp_data=1&filters_initial=1&filters_changed=0&qtranslate_lang=0&current_page_id=4453&asp_s=

The column on the left shows all categories for CPT “Resources”. We have a parent category “Videos” with various child categories, such as “Product Demo”. All of the posts are assigned to BOTH the parent and one of the child categories. The problem is that people naturally click just “Product Demo” when filtering and that returns zero.

Am I going to need to change the assignments such that all posts belong ONLY to the lowest level (child) category? Or is there a setting I could use so that if someone checks just “Product Demo” they get all those videos without having to check “Video” + “Product Demo”.

Just seeing if there’s an easy way before I re-do all the category assignments.