Change Time to Militairy time (ex: 12:00)

On all of the reservationpages the time stamp in writing with pm and am, I would like to change that to 12:00. (in wordpress I selected the 12:00 timestamp, but your plugin wont work with that timestamp and stays on pm and am.

Any ideas to update this?

The page I need help with: [log in to see the link]