Preferences

General program options, such as cursor shape, axis color, zoom factor, and display of coordinate system icons.
 

Coordinate system icon:

You can choose to display the User CS and/or World CS symbol/s.
For both, you can set the color of the axes and size of the icon. 
For the World CS, select the corner of the screen where it will be displayed: TopLeft, TopRight, BottomLeft, BottomRight

Drawing cursor

Cursor Shape: Select one of the three shapes provided.
Show crosshairs: Overrides the normal cursor, displaying a screenwide horizontal and vertical line intersecting at the cursor position.
Show Isometric: Overrides the normal cursor, displaying all three axes.
Show Snap Aperture: Displays a circular area around the cursor whose radius is the Aperture Size. Aperture is used while snapping, to detect objects.
Aperture size: Specify the radius of the aperture in pixels.
You can also use the View | Display | Cursor menu to change the cursor display.

Undo/Redo

Undo/Redo depth: Sets the number of operations stored in the Undo buffer.
Include Model / Paper space switch in Undo buffer: If checked, switching between Model and Paper spaces will be included in the Undo buffer.

Selection

Use Choice if several entities in aperture while selection: If more than one object lies within the aperture area during a selection, a small window appears from which you can select the desired object.
Visual Effect Settings: Settings for the various "highlighting" methods. See Selection Visual Effects Settings.