Some date formats can be modified by changing preferences in Config. editor:

http://kb.mozillazine.org/Date_display_format

Hello sfhowes,

Thank you for your quick reply. Under Windows settings, I saw that the date and time are correct for my location. I can't change anything more because I don't have any computer skills to make further changes. I have no programming skills. Could there be an easier way to change the date in the Thunderbird email program?

What is the current date format, and what do you want to change it to?