Q: iTunes and voice memos

What you see in the iTunes window does not necessarily have anything to do with the actual file name. I believe voice memos having numbers as names is standard.  Once you have the memo copied out of iTunes you can re-name it as you would any file.  There are ways to re-name it inside of iTunes but that can mess with the interface and I wouldn't do it unless you are answering questions here instead of asking them.

The files were not named in iTunes. What you see in iTunes are tags which are labels stored inside each audio file.

http://dougscripts.com/itunes/scripts/ss.php?sp=filerenamer

So you made a mistake in not realizing what you were doing wasn't renaming your actual files. Now you have learned something. Use the tool I linked to remedy your mistake.