Just to be 100% clear, so we’re on the same page – in your picture where it says
- Release Notes
- User Questions about Images
- Test Topinc in Top Level Category
Those topics you see there can come from either
- “Discussion for Users” parent category
or
- any subcategory of “Discussion for Users”
In other words, the “Latest” field here reflects the latest topics in any subcategory under Discussion for Users, including topics in the parent category alone.
(Also, I’d be really careful with extra long and wordy category titles like “Discussion for Users” as Discourse is a discussion solution; the discussion part is implicit. Better to make the category “Users” and have the extended explanation of what the category is about in the category description.)