Firstly, make sure it is in the Timekeeping Mode.
DST Setting / Module : 3502
<Timekeeping Mode Screen>
To return to the Timekeeping Mode,
hold down Ⓒfor two seconds.
In the Timekeeping Mode, hold down
Ⓐuntil the seconds start to flash.
Date
Time
Second
Press Ⓒonce.
"Hours" will flash.
Press Ⓓto change the hour.