I am noticing the same that the newer versions of QU now prints "ModifyDate" instead of "CreateDate" if I select to print EXIF details on the edge.
I cannot fault QU here. See attached screen shot of a 2009 image which I modified in QU today.
The Info stamp date and the Floating Text date/time are for when the image was taken.
EDIT. are you editing the image in another program which is modifying the EXIF date taken?
Terry