Profile>> Profile Information>> Selecting Your Timezone
The timezone option appears first while registering to a community. It helps us to select a timezone of our choice. By default the timezone is America/ Los_Angeles. To edit the timezone you could simply change it from Profile section.
Any export or import done by the administrator of the community will allow them to select a timezone of their wish. However any automated email or notifications triggered due to any idea or comment submitted in the community or broadcast emails or any other kind of scheduled emails will not be as per timezone selected.
In terms of a normal user it is an option which they can select from Profile section.
Please look out for more updates in near future.