Hi
I am new here, but worked with inkscape for a year or so, normally no problem at all.

But now I need to change a lot of old files made in CorelDraw and saved in *.emf. But when I open them in Inkscape are all measurements in px. I try to convert the display unit to mm in "Document properties" but it keep changing back to px.
I tried to go all objects over and change all tools to mm, but in keep changing back to px.

What did I miss?

Please copy the version and build number from the Inkscape Help>About page and post it here.
IIRC there were some releases with units not setting properly.

Thanks.

Inkscape 0.92.1 r15371

OK, could be related to this: https://bugs.launchpad.net/inkscape/+bug/1671059

But I would try opening the file, copying the contents to a new empty document and see if that works. Ensure size of objects is correct.

Feel free to attach a zip file of an example (or link to a file on a hosting service like dropbox) , if you would like us to test.

TD

thx. copying the content into a new document works.

But i still think it should be possible just to change inside the existing file.