IOS & Android
The app uses the time zone of your device
The poll uses the time zone that the user set in his phone or tablet settings. It happens all automatically.
If a participant opens a poll with time zone support in the app, a message is shown if the poll uses a different time zone than the one set in the device settings. The times are then automatically converted to the time zone of the device.
If you wish to change the time zone for the poll you create in the app, you have to change the time zone of your device. Alternatively, you can create the poll from the web in any time zone you would like.