To change the time on your Braun alarm clock from 12-hour format to 24-hour format, follow these steps:

1. set the switch to the neutral position, if available, or to the time mode if this switch is not available.
2. press the "+" button to switch between the display modes.
3. if the switch has been set to time mode, return it to the neutral or off position to save the setting.

If you have problems, check that the switch is positioned correctly and that the "+" button is pressed correctly.