Using the Ambient Settings tab of the Drawing Settings dialog box, you can specify default ambient (background) settings for a variety of features, including some that affect units of measurement. These settings control parameters such as angle, area, direction, elevation, and so on. There are also settings that affect the Event Viewer, tooltips, and how curb returns are created for intersections.
As you select a parameter, the description in the lower part of the dialog box reflects the selection.