You can change the unit in Options -> Doc Properties -> Units to centimeters.
A another good approach, is to model in one unit system and dimension in another.
You can create a dimension style that has text that represents the part in centimeters, even thought the model unit is meter. See the attached example 3DM.
If you have a model that is not changing unit when you select it, please post it or email tech@mcneel.com.
We are happy to take a look at it.
Sincerely,
Mary Fugier
