I went from 3.3 running on XP to 4.92 on windows 8. The restore command would not accept the file name.
The only extra step I took was to run a back up of the new software to the location of the old back up. So:
Install new software on the new computer, then run accounts back up to the destination folder where the back up "old" resides. Then run "restore" back up on the new computer selecting the "old" file. I suspect the dates of all 3 files need to be the same so do all 3 the same day.
It imported all my old data perfectly. My suspicion is that the software cannot be restored until it has actually been created by the data hence the same day for all 3.
Hope this helps