Display message threads switch default setting (Linux)

[Budgie3]

Dumb question but how do I change the default switch setting for the left hand column "Display message threads"
This has started being turned on as the default setting, not by me intentionally and I want to turn it off until I need it with a click not the default.
Cannot find the switch yet.

[morat]

The "Thread" menu item in the "Select columns to display" menu popup enables or disables the "Display message threads" column.

Do you want to change the default threading mode?

Message threading - Changing default threading mode
http://support.mozilla.org/kb/message-t ... ading-mode

[Budgie3]

I could switch off the selected column but would prefer to have it so that the column is visible and I can toggle the threading mode. At present the column default to threading mode with threading enabled. Not a big deal for me but just asking. I appreciate that most people will want the threads to show.