When new users are added they are initially set up with the time set to UTC (GMT). For most users this is not appropriate and they need to go into settings to set their own time zone. This even applies to users in the UK who need to select London in order to get the daylight saving time applied automatically in the summer. If we could have the facility for an administrator to set the default time zone for an account then most new users would be set up with the right time.