I hadn't had this problem when I was working on my Mac @ work, but now I'm working on my PC from home, this has been driving me crazy.
I may have stumbled upon a fix, though.
Open Illustrator
Change unit preferences to required units
Create a new document, making sure you switch to required units before creating
Close document and Illustrator completely
Units should now stick (well they did for me)
I hadn't had this problem when I was working on my Mac @ work, but now I'm working on my PC from home, this has been driving me crazy.
I may have stumbled upon a fix, though.
Open Illustrator
Change unit preferences to required units
Create a new document, making sure you switch to required units before creating
Close document and Illustrator completely
Units should now stick (well they did for me)
Hope this is of some help.