Yes, the the right bottom button is used for switching between 24-hour format and 12-hour with am/pm notation. If you look closely at the photo’s in this thread you can even see the text pointing to the button indicate this 
I think this button is also my greatest complaint about this watch, it’s really easy to press this button accidentally, I prefer keeping it in 24-hour mode but through normal wrist motion throughout the day I often end up switching modes without wanting to.
