Changing the units in OptiCut is quick and easy.
Click on Tools > Units
You can change the units for the Length, Surface and Angle.
You cannot change the currency in OptiCut.
OptiCut pulls the currency setting from the Windows operating system.
To change it, go into your Windows Control Panel, and change the locale or region so it relates to one with the currency you require.
Please go to this page for more details on OptiCut.