If anyone gets confused (like I did) about the inaccuracy of the mouse pointer on the Scroll View scrollbars, note that the custom white arrow cursor in the course project is not set up with the tip of the pointer at the mouse hot-spot, which means that the hot-spot is actually nearer the centre of the white arrow, so it feels like the scrollbar is slightly to the side or above where it is visually. No amount of moving the Scrollbars and Viewport will fix this issue.
I know it may be obvious once stated, but I wish I could have told myself this an hour ago.