Not everything is so straight forward on them however, especially cron. If you have done any work on a Linux box you have encountered cron. Most people edit cron jobs using a web interface for their hosting company, but QNAP boxes are not hosting companies… You would probably try crontab -e to edit the list of jobs right?
Problem is, changes you make do not persist across reboots. A real pain-in-the-butt if you forget that and reboot to find out your jobs are not running like you thought they were.
The trick is you must directly edit /etc/config/crontab file, make your changes there and they will then persist across reboots OK.
QNAP has done a WIKI page about editing cron jobs on their website.