To set a time zone for your organization start by selecting the dropdown at the top left of your screen and then select .
You can then select the tab on the left. In the Time Zone panel you can pick your desired zone. All reminders created in the organization will be created in this time zone.
If a member of the team is in a different time zone they will get an indicator to let them know that the times on the reminders will be shown relative to the time zone they are currently in.