To change default drawing parameters, colors, and units, choose File > Preferences and then click the Measurements tab:
Use the Fixed angle box to specify the default angle used when drawing rings and bonds. The angle is constrained to increments of this value.
Use the Hot object size to change the size of the selection highlight.
Units for the hot object (selection highlight) size are set in the Dialog Unit drop-down list in the Units section.
Select colors for Pivot atoms and bonds and Chemistry Checker errors using the controls in the Colors section.
Select units for the Ruler and Dialog in the Units section.
See also