If you look in the ftp config file, /etc/proftpd.conf, you'll see what the permissions are.
If you want something different you'll have to modify the config file yourself. To do so you'll have to read the files in
/usr/share/doc/proftpd-1.2.0rc3/
to learn how, and then make modifications to the e-smith templates.
There are security issues with ftp (eg, cleartext passwords). I believe that it is possible to set up proftpd to use its own password file and to give any users access via password to ftp only. I have selected the "disable ftp entirely" option on my servers.
I would suggest getting your users to use scp instead of ftp (which is what I have done). There are clients for MSWindows and macs available via links on the openssh.org site. Other than having to install the client, it is no more difficult to use than ftp.
Chris