macOS can be set to either behave the way you're describing when you click above or below the scroll thumb, or to navigate to that point in the document when yo

macOS can be set to either behave the way you're describing when you click above or below the scroll thumb, or to navigate to that point in the document when you do that (e.g., click 80% of the way down the scrollbar and jump to the 80% point in the document).