I am not seeing the exact problem or solution that I need. I have never used threaded messages. Now with the latest update I sometimes open a message and have all of the "threaded" messages also open? I am just clicking on one message and sometimes this happens.

It's annoying that something seems to have been added or enabled by default without asking us first. And it's more annoying that it has not been fixed yet.

I have Thunderbird 115.8.1, and I have been trying to permanently eradicate threaded view for all folders and subfolders. Can't do it. Tried the film strip goodie at the uper right, tried view > sort by > unthreaded a bazillion times, it keeps coming back. I also remove the threaded column from the view.

Please, please, Thunderbird developers, give us a way to turn this off permanently, forever, through updates, hell and high water. Is there a way to do it with a config file, or with microsoft regedit?

Thank you Mike

I've also been encountering this problem. I'm hoping that upgrading to Thunderbird 115.8 or above will fix it.

As per this Bugzilla ticket, prior to version 115.8.0 there was a bug where folders reverted to threaded on being compacted: https://bugzilla.mozilla.org/show_bug.cgi?id=1725127

I am running 115.8.1, and I finally don't get threaded messages when creating a new folder, with mailnews.default_view_flags set to 0.

However, I cannot for the life of me figure out whether I can change the column layout for new folders without having to go through the "Select columns to display/Apply columns to" and the "Select columns to display/Apply current view to" rigmarole.

I help out less-savvy family and friends with Thunderbird all the time, and I've recently been creating new folders for number of people, and find myself having to go through this "apply" process repeatedly. It gets old.

Also, repairing a folder threads things again, and resets my columns to "default."