Only show Commens in category or hide in category

Hi guys,

New category gets automaticly comments.
I would like to say show only the comments in category blog, and all subcategories.

Or/and do not show in categorie, and all subcategories.

Why?
If i only use it in one categorie it is bummer if customer adds a new category in frontend. Now they need to go to backend and know where to find this hide category option.