From MEPIS Documentation Wiki
Setting The Time Zone
Using Control Center
From the menu select Control Center, then System Administration, then Date and Time.
You must click on the Administrator Mode button and enter the root password to change the time zone setting.
You can now select a city that is in your time zone.
To move quickly through the list click on any entry and then press the first letter of the city you want to choose and you will be moved there.
By default the list is sorted alphabetically by city names. To sort by another heading click on that heading.