We are currently working on a file which will enable the LED-Nixie clock to display the time in the 12 hour system. The Windows software that is provided along with the clock (see download link below) allows you to apply the file to the clock.
Please read the section “Customizing the LED-Nixie Clock” to find out how exactly you can change the settings of the clock.
Download “Basic-Editor” (freeware, open source, Windows, English is included):
https://www.led-genial.de/LED-Basic-Downloads