If you are a registered user, all your settings are stored in the board database. To alter them, visit your User Control Panel(UCP); a link can usually be found at the top of board pages. This system will allow you to change all your settings and preferences. Most options within the UCP are fairly staightforward though please feel free to ask in the Questions, Tests and Comments forum for further assistance if you are unable to find what is needed.
It is possible the time displayed is from a timezone different from the one you are in. If this is the case, visit your User Control Panel and change your timezone to match your particular area, e.g. London, Paris, New York, Sydney, etc. Please note that changing the timezone, like most settings, can only be done by registered users. If you are not registered, this is a good time to do so.