Sentry self setting atomic clock lost the instructions

Select The Time Zone - For Sentry Self-setting Atomic Clock (ATC - 10)
The default time zone is Pacific zone.
1. In the normal time mode, press the MODE key to enter the alarm time mode.
2. Press the SET key to change the time zone.
each press of the SET key will move the time zone back one hour
P= Pacific M=Mountain C=Central E=Eastern
3. Press MODE key when correct Time Zone is highlighted.

I think the Instructions may tell you to use the ADJUST key instead of the SET key.
ADJUST key does not work for TIME ZONE change, SET key works.
This will set your clock to your chosen Time Zone for normal time.
Instructions for the ATC20 are located at the following url
http://www.sentryindustries.com/pdf/instructions/ATC20_instructions.pdf