Hello,
All Clockys have the same software that allows them to have either a 12 or 24 hour clock. To start 24 hour clock, you must press and hold the T button. If you are in 12 hour mode and in one of the PM hours, when you press and hold the T button, you will see a change on the screen to the corresponding 24 hour number. If you are in 12 hour mode and in one of the AM hours, however, you will not see a change when you switch into 24 hour mode. So please make sure you are in one of the PM hours and try pressing and holding the T button.
Thanks,