Firstly, make sure it is in the Timekeeping Mode.
DST Setting Module : 5230
To return to the Timekeeping Mode
from any other mode, hold down (C)
button for at least four seconds.
<Timekeeping Mode Screen>
City code and city name
"SET" will start to flash in the left digital dial.
The city code and city name will scroll
across the right digital dial.
In the Timekeeping Mode, hold down (A)
button for two seconds until ADJ appears
in the right digital dial.