To update the timezone for all times in your report, navigate to the SCRIPT section of your report and add DATA.timeZone = "your time zone" to the top of the script. Full list of timezones can be found in the TZ identifier column of this table.

DATA.timeZone = "Australia/Sydney"; // Update all times to Sydney, Australia's timezone
DATA.timeZone = "America/Phoenix"; // Update all times to Phoenix, USA's timezone