Select Settings > Units.

System Units

Sets the unit format for the device.

Variance

Sets the magnetic declination, the angle between magnetic north and true north, for your present location.

North Reference

Sets the direction references used in calculating heading information. True sets geographic north as the north reference. Grid sets grid north as the north reference (000º). Magnetic sets the magnetic north as the north reference.

Position Format

Sets the position format in which a given location reading appears. Do not change this setting unless you are using a map or chart that specifies a different position format.

Map Datum

Sets the coordinate system on which the map is structured. Do not change this setting unless you are using a map or chart that specifies a different map datum.

Pressure Reference Time

Sets the reference time used to calculate the barometer trend. The trend is indicated in the barometer field.

Time Format

Sets a 12-hour, 24-hour, or UTC time format.

Time Zone

Sets the time zone, or allows automatic selection based on GPS location.