Always install the latest version (0.9.60.2 currently).
To (again) re-quote @botg:
It should suffice to copy FileZilla Server.xml while the server service isn't running.
Discover changes between your version and the latest (quite a lot for you to read): https://filezilla-project.org/versions.php?type=server
Needless to say that running such an old, vulnerable version for such a long time is borderline criminal (if Internet-accessible).