Use the Ruler Settings command to modify the appearance of the current picture's on-screen rulers.
Select the desired Unit of Measurement. Available measurement types are Pixels, Inches, Centimeters and Points. The measurement type also can be changed by clicking the button located at the upper left corner of the picture window when the ruler display is turned on.
Enable or disable the Show Rulers option to show or hide the rulers. When the Show Cursor Position on Ruler option is enabled, two small markers will appear on the ruler showing the exact position of the mouse cursor.
You can customize the ruler's appearance by changing the Foreground and Background color. The ruler Preview will show how the new colors will look.
Check the Default option to apply your ruler settings to all future pictures. The next time you open a picture, its ruler will automatically use these settings. If you do not check the Default option, only the current picture's rulers will be affected.