Overview – Time Zones
The default time zone is Eastern Standard Time (US & Canada). Any bookings created on your site are created in this time zone.
If you decide to change to a new Time Zone, all of your existing Bookings will still be stuck in the OLD Time Zone.
This is why there's a brief explanation next to the Time Zone setting: "NOTE: existing bookings' time will change if you change timezone."
Example:
In 'Eastern Time (US & Canada)' booking was made for 9:00 AM. If you switch your timezone to 'Pacific Time (US & Canada)', the same booking will be for 12:00PM.
So, after you change your Time Zone, you will have to go through all of your existing bookings and change the booking times to the correct times.
How to Safely Change your Time Zone:
IMPORTANT: Go to Bookings -> Download CSV, choose the 2nd FORMAT and download a spreadsheet of all of your existing bookings — so you know what the original booking times were!
Go to Settings > General > Subdomain tab and change your Time Zone (please note how many hours ahead/behind your new Time Zone is to the original).
Go through each of your existing Bookings and change the booking times to the correct one.