You can change the Passive FTP Port running the commands:
echo "PassivePortRange: 55536 56047" >> /var/cpanel/conf/pureftpd/local
/usr/local/cpanel/scripts/setupftpserver pure-ftpd --force
Change 55536 56047 with the port range, you want to set it to.
More information here:
You will need to make sure that your Passive Port range are already not in use and you've allowed access in your firewall.