The Government changed the dates for daylight savings time starting in March 2007. Under the new guidelines, daylight savings time will start on the second Sunday each March and end on the first Sunday each November. In 2007, these dates are March 11^th and November 4^th.

If you have an older DST clock, chances are that the movement in the clock has the "old" daylight savings effective dates programmed into it (April and October). The quartz movement will continue to keep time properly, but you will need to turn off the "DST" function so the time does not automatically change on the "old" daylight savings dates.

If you have an older DST clock, it may have the "old" DST dates programmed into it (April & October). In order to have the clock to run without the dates automatically changing, you can turn the DST function ‘OFF" and the clock will operate like any other standard quartz movement clock.

To turn the "DST" function off, please follow these steps.

1. You will need a copy of the operating instructions for your clock.  If you do not have the original instructions, you can scroll to the bottom of this answer and click on "Click to enlarge image" to see a copy of the instructions.
2. Remove the battery and reinstall it.
3. Once the battery is reinstalled, the "Set Up" screen will appear in the LCD display
4. Follow each step in the set up/operationg instructions.
5. In Step #4, of the instructions, it describes how to turn the "DST" option "On" or "OFF. You will need to select the "OF" or "Off" option at this time. This will turn the "DST" option off.
6. Once this is done, complete steps #4 - #11. This is necessary in order to complete the programming change that turns the "DST" function off.
7. The clock should now have the "DST" function turned "Off" and it will operate as any other non-DST quartz movement.
8. You can now change the time manually using the time set knob on the back of the clock.