Inherit means it inherit the settings from its parents (in the HTML structure)
If someone used a lot of custom CSS to change things and override the theme settings, you need to inspect the page with your browser developer tool and check what rule is giving the element its style, and either modify their CSS, or use the same rule with your modified property and a specialized selector.
If this is above your head, give us a link to the page showing the element with specific detail of what element and what property you are trying to change