On 06/24/2018 11:56 PM, Ken Heard wrote:
How do I get Thunderbird to use the same format for dates/times more than a week old?
You need to use the config editor to create/edit mail.ui.display.dateformat.today, mail.ui.display.dateformat.thisweek, and mail.ui.display.dateformat.default as Integer prefs. It sounds like you want 2 for all of them.
http://kb.mozillazine.org/Date_display_format has full documentation.