Had a hard time doing this and saw nothing on the net. I had to guess how to do it by pushing the calculator buttons on my watch.
So I decided to write a short how to so you can do it easily without reverting back to your manual.
Push the adjust button, the one that's colored silver.
Once you have done this, the hour button will blink. Just press the button + and it will shift from military mode to am/pm mode. Thats it.
Additional info. If you want to see the date on this watch just press the divide button,
Hope this helped you somehow. Hehe