Illustrator Will Not Save Unit Preferences

[Wideformat5C7C]

Illustrator (25.2.1) will not save any of my preferences for units. Every time I set the units to inches and quit Illustrator, it reverts back to pixels when I open it again. It saves all of the other preferences I've changed besides units.

[Monika Gause]

Exactly when does this setting back happen?

When you open a document?

[Wideformat5C7C]

I have to set it in preferences everytime I start up Illustrator.

If I quit Illustrator and then open it again, it will reset the units back to pixels.

[Monika Gause]

If this is not related to opening a document, then it might be preferences corruption.

The units are a document based setting and what you set up in the preferences does not affect existing Illustrator documents.

But it should keep the settings in the preferences. You could try and rename the preferences folder. Illustrator will then create new preferences. https://helpx.adobe.com/illustrator/using/setting-preferences.html

[Ton Frederiks · Accepted solution]

Once upon a time (to be specific the CS apps time). You could change the unit in the Preferences without having an open document, quit the app, reopen it and the settings were kept.

As far as I can check (CC2017) this does not work any more, the old settings are kept.

Not that it matters much, creating a new doc with a different unit will change the prefs unit setting.

[Ton Frederiks]

Other parts of the preferences will stick when changed without documents open, but the units won't. So preferences are saved.

[William5C09]

I usually bring in .DXF or .pdf files as a starting point so I am not creating a new AI document when I use Illustrator to open these. I used to have the Preferences/Units stick in mm but now  I have to set the scale and unit preference each time I open a file. It is important for what I do to keep the scale accurate to the mm level. Is there a way to always open files assuming I want to use mm?

[Monika Gause]

Units are a document based setting.

[Ton Frederiks]

And if the document (DXF, PDF) does not have a setting it uses the current Preferences setting.

But I think for DXF files, the problem is that the plugin does not remember option settings.

[John Mensinger]

Helpful, or maybe just interesting...

https://community.adobe.com/t5/illustrator/units-preference-won-t-stick-in-illustrator-2018/td-p/946...

[Woody16B8]

I was having the same problem every time I started a new document too, but I think I found the fix. If you notice there is a choice of size documents to open and for some inexplicable reason the "Letter" is set at POINTS in the fine print so I created a new "Letter" size in the box on the right with Inches and saved it. Now when I want a new Letter size file in inches it's right there.