Taking a look on my own Fetch box I can't find a setting option anywhere for this.
KHe, does your Fetch box have the wrong time set? Or are you getting prepared to change all your clocks for daylight savings and Fetch is on the to do list 🙂
Confirmed by a Fetch guide from another RSP: the timezone is provisioned by the RSP/ISP. So, please contact Optus to have it changed (or Fetch if it was not supplied by an RSP).