How can I change the 24 hr format to 12 hr format?

To change the clock format, visit the General section of Momentum's Settings ??, scroll down to the Clock Format option and then click 12 hour or 24 hour to the right of it. When you switch to the 12-hour format, the AM/PM unit will display for a moment and then fade away to keep the interface clean.
https://get.momentumdash.help/hc/en-us/articles/360022896993-How-can-I-change-the-clock-format-12-hour-24-hour-

https://www.youtube.com/watch?v=VfthmmTM7Oo

Was this problem answered? If yes, can somebody tell me how. My Casio LA670W is in 24hr format and I want it back on 12hr format. My watch have 3 buttons only. Mode, Start-Stop and Timer

Press and hold LAP/RST button. It will display "SET" on the screen. After that, use MODE to switch between second, minute, hour, date, month, 12-Hr/24-Hr format, day. Use STS/STOP button to change the values of each. It will guide you with arrow on the screen. After setting all the values, press LAP/RST again to take you back to the original time.

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• Press "MODE" (lower left hand button) three times to get to the screen where the numbers are blinking, indicating that you can adjust the time
• Make note of the hour if you don't have another clock handy
• Press "LAP/RST" (lower right hand button) once to get the hour numbers to blink, indicating that you can change them
• Press "ST/STP" (upper right hand button) to move the hour forward until you go past 24
• At this point, you will notice a little "A" next to the time to indicate AM, and if you keep going past 12 hours, it will cycle back to 1, this time with a "P" next to it to indicate PM

Press and hold the SET button (it will read CHIME with a flashing on or off). Then push the MODE button - the top will be flashing 12-HR or 24-HR. Push the ST/SP button to toggle between the 12-HR to 24-HR reading. Push the MODE button to get to the hour/minute/second/year/mo-day/month/day value you want to change. Push the ST/SP button to increase the value, the RESET button to reduce the value.

Go to:

http://ftp.casio.co.jp/pub/world_manual/wat/en/qw2016.pdf

Full user manual and instructions there to download.

armitron watch 40/6601 instructions

NOTE: 12/24 HOUR TIME IS SELECTED BY PRESSING RESET/LIGHT ONLY WHEN THE HOURS MARKER IS 
FLASHING. THE “A” OR “P” WILL DISAPPEAR WHEN THE 
WATCH IS SET TO 24-HOUR TIME.