Yes you can.
When you register for ServiceM8, the system will automatically detect your location, and setup your account accordingly, including:
However, sometimes this is not useful (especially if you're an Irishman living in Indonesia). So you can change the settings yourself. To do this:
Login to ServiceM8
Adjust your timezone, and language settings accordingly. Note your currency is linked to your account region/language choice.
Once you are done, please don't forget to hit Save.