Here is official info: https://support.mozilla.org/en-US/kb/message-threading-thunderbird The link also explains how to use config editor so that all future folders you create are unthreaded.

On your question: - set one folder to your preferences and highlight it - click the icon on right side of the menu bar of message list pane as shown on web page - click to apply current view to> and highlight 'folder and subfolders and PAUSE - a menu opens to left with account name. highlight that and PAUSE - another menu opens to its left with account name at top. CLICK THERE and a confirmation message will appear to confirm setting all folders in the account.

That's brilliant David

It was the menu bar setting. It wasn't showing up on the right.

All sorted now

Kewl!  :)

Still didnt get this, until I worked it out myself by mistake.

For PC users using 115.10.1...

1. right click next to the search bar, somewhere between the hamburger and the search bar 2. 'menu bar' displays in a new drop down with 2 options 3. Click on menu bar, this will show a new menu bar with 'file' 'edit' 'view' etc 4. select the folder you wish to change and click 'view' 5. got to 'unthreaded' 6. messages in that folder will unthread

Not sure how to do this for all folders, but it works one by by using these steps.

Craig

If you click on "Inbox" and go to the right hand side and "Choose Columns To Display", a menu comes up, choose what you want and then the bottom 2 options are:

"Apply columns to" "Apply folder view"

Hover over those and choose which folders/subfolders you want it all applying to and hey presto, it works for all.