Units in parts

Before starting to create a new part, I go to options,- document properties, units, and then I pick mmgs . and click OK.

I want this to be default for all my parts.

But every time I start creating a new part, I have to go thru this procedure again. (very annoing)

My SW always go back to IPS   (inch, pound, secund) as default.

How can I get mmgs as default ?

 

I use Parallels  on a mac-book pro

 

Thanks   POUL