The middle and right button overrides can be used to temporarily select any of Stradview's tools when you depress the appropriate mouse button. Releasing the button returns the tool selection to its original state.
The 'Mouse selection range' slider determines how close the mouse needs to be to any object in order to select it. If you want to point less precisely, set this to a larger value, but not so large that you find yourself selecting objects you do not wish to select.
The 'Cursor rotation' slider determines by how many degrees the 3D window or reslice will rotate when the cursor keys are used.
The 'Cursor move' slider determines by how many pixels the image or ortho windows will move when the cursor keys are used.
The 'Scroll zoom' slider determines by what percentage the zoom will increase or decrease when the mouse scroll-wheel is used in any of the image or 3D windows.
Selecting 'Use scrollbars when zooming' controls whether to show scrollbars in the image or 3D windows if they are zoomed such that not all of the data can be seen at once. If this is not selected, panning is only possible by using the right mouse button. Some graphics drivers do not work correctly with scrolled graphics windows and either display the image in the wrong location, or cause mouse clicks to be in the wrong location. In this case, disabling scrollbars should fix this issue.
Finally, selecting 'Expert mode' suppresses some of Stradview's warnings and checks: Stradview will then just do some things without asking "Are you really sure?"
All these settings are saved in your personal configuration file ('stradview.ini') so there is no need to reset them every time you launch Stradview.