I have a file where the artboards and paths have been specified in mm. I want them in points. I confirmed that I had points set in my preferences, and opened the file. everything is still showing in mm. So I save it, closed it, and opened it again - no change. How do I get AI to convert o my preference?
Once a file is created, it keeps whatever units were set when the file was created - individual files do not change units based on your application preferences.
You will have to change the unit preferences for that file with that file open. Changing preferences will all files closed changes them only for future new files.
Changing preferences will all files closed changes them only for future new files.
Changing Preferences does not affect New files. It only affects files not created in Illustrator and opened in AI (like jpegs, tiffs, pngs).
New files get their units from the New Document Profile they are using.
With you file open, go to File > Document Setup and change the units.
Or Ctrl click in the intersection of the Rulers to change units.
The Preference setting is as far as I know only used for documents like jpegs, pngs that are directly opened in Illustrator.
I didn't know about the shortcut of Control click in the intersection of the Rulers to change units.
Much better than having to change units twice in the preferences!
I have seen a bug in Illustrator that sounds like what you're describing. The document will be set, for example, to inches but something I've selected will show as points in the Transform Panel. I've found that the fix for this is, while the file is open, to change the Units General preference to something other than what you want then click "OKAY" then go back to Units in the preferences and change it again to what you actually want the Units to be. This workaround has always worked for me. This bug has been driving me crazy since the 1990's!