How do I update the policies and settings for each category?

Just tap on the ⚙️ gear icon for the service category that you'd like to update settings for. 

This takes you to your Category Settings page, opened up to the category corresponding to the gear icon that you had tapped on the previous page. Here, you can customize your settings for each category (just tap the category you'd like to update on the left!) under whichever type of setting you'd like to change (see the three tabs at the top of the screen):