Taxonomies | WordPress.org

Hello! I am setting up my first saved layout. I would like the filter at top to only show certain categories, so I chose them under Posts Settings > Portfolio> “taxonomies” but it’s showing more than the categories I selected. For example, I chose “Category A” & “Category B” under taxonomies for this saved layout. But it is also showing “Category C” in the filter at the top. Is this because one of the projects in Category A is also in Category C? Any way around this? I want the filter at top to match the taxonomies I chose.