Setting project units
To change the project units, open the main menu dropdown and go to Project → Units.
Units currently supported are feet and decimal inches, millimeters, and meters. The default for project units is feet.
You may change the project units at any time and all existing units in the project will update automatically. Inputs also support entering any unit format regardless of the project units (eg. if project units are feet, you can still enter something like 5m when drawing a line and the conversion to project units will be done automatically).
Unit precision
Unit precision can also be set in the units menu. The precision can be changed at any time and all existing units in the project will update automatically.
Project unit settings are persisted to new projects, so whatever you set the project units to on your most recent project will be the default setting in a new project.