Login your server on ssh.
Step -1 =) FTP Settings File Edit
nano /etc/pure-ftpd/pure-ftpd.conf
Step -2 =) Find line : #Bind
Click CTRL + W - write #Bind and push enter.
Step -3 =) Adding line new port:
http://prntscr.com/f0tvk9Bind PORT
Example for port 211:
Bind 211
Last Step -)
service pure-ftpd restart
Do not forget to open it in the firewall you are using your new port.