sudo nano /etc/default/openhab
Replace “nano” with your preferred text editor.
Since this was posted I think we found the culprit. If you did not edit /boot/openhabian.conf before the first time you booted as the instructions describe, you didn’t set the timezones for openHABian. Consequently the default timezones was used. And that file gets copied to /etc/openhabian.conf. Every time openhabian-config runs it resets everything based on /etc/openhabian.conf.
To prevent/etc/default/openHAB from being changed in the future, set the timezone in /etc/openhabian.conf too.