Image units management

Hi,

I just saw a video tutorial on how to "Creating your Drawing Settings and Drafting Standards in DraftSight"and there it is shown how changing the drawing units (from the user preferences) for a file reflects in a change in those units themselves (from inches to millimeters for examples) in the drawing. I have tried to do this in different files or even in the same file, by for instance inserting a block or a line which is defined in inches and changing the user prefs by setting mm as the units, and nothing seems to change when in the tutorial one can see that by inserting the same block under two different units systems the (visual) size of the block changes.

Generally speacking, how can I be sure that a given size is in a certain unit? It would help that if along the measurement (as given by the GetDistance command, for example) the unit of measurement would appear just beside

For example on ethe typical tasks that I do is to insert a drawing in DraftSight that represent an element in a landscape
so what I want to be able to do correctly is to scale the drawing appropriately so that it conserves the right propotions with the real thing AND use certain specific types of units (like meters or mm) so that after scaling my draing into draftsight I can continue drawing knowing that whatever I draw after will use the same unit

Any help appreciated