Sorry, there is no such setting. There are two options that I can think of:

  1. START OVER: 

To do this, remove all accounts. Then, go to settings>general and scroll down to config editor and set

  mailnews.default_view_flags    to 0    That will set unthreaded as default for new folders 

now add accounts back and the folders should default to unthreaded 

  2. FIX IN PLACE: 

This is the other option, setting to default after setting up accounts:

To change default for new folders, In config editor, you can change default that applies to NEW folders you   
 set up:
 mailnews.default_view_flags      0=unthreaded  

Config editor is available at Tools>settings>general and scroll to bottom right.

 ------------

To set many *existing* folders, follow these steps:

  In the Message List view, in the column header, on the far right, open the options button that shows    
   context menu. (See attached screenshot):
  At the very bottom is the option:
  -> "Apply current view to..."
  -> "Folder and its children..."
  -> Hover over an account
  -> In the next menu don't select a folder. Instead select the account name itself.

This isn't a perfect solution, but it does address the issue of unthreading many folders.

OK lon the mass try do I have to go and do it to the final destination as seen here?

I believe going back to account level is all you need, done separately for each account.

So in each as in the red arrows or what makes more sence each as in the green arrow yes?

I am having difficulty following your chart. I think red will do it, as that appears to be the root of the account.

The RED arrows are the 4 different e mail accounts. the green is like one account

Joe

I can not seem to break any of this Threading! UG!

I would do each of the red separately, as the solution is account-oriented.

Sorry I clicked the resolved button. Will try the Red ones and see what happens.

What Pisses me off is I have been telling the program probably for 6 months or more NO I DO NOT WANT TO UPGRADE TO THE NEW PORGRAM YET.

Then one day it just did it without asking even tho I clearly had all the setting to ask but not do it. But it did anyway. and then made all this threading crap! Hopefully I only have to try to do this on each of the accounts and not each folder. because I litterally have 10+ years of folders and hundreds of them for each account.

Look at this Tree, thats only like 1/2 the visible list of one account and look closely those are the main folders, inside each of them are sometimes 100+ more folders in each one!

UPGrading all by itself was bad enough but then to change settings when doing so is just poor thing to do!

The default setting was a decision made by the developers. I'm not saying I agree with it.

The advise given by David to set up the following will solve the problem on new folders.

• mailnews.default_view_flags 0=unthreaded

Regarding the other setting: For the nss mail account Select the Inbox Select an email in Inbox Set 'View' > 'Sort by' > select 'unthreaded' This will get one folder corrected then use the settings David advised.

1. In the Message List view, in the column header, on the far right, open the options button that shows context menu.
2. "Apply current view to..."
3. "Folder and its children..."
4. Hover over an account - Select the top red nss account
5. In the next menu don't select a folder. Instead select the account name itself - select same nss account (green).

You will get a pop up saying to apply to all folders in the account. then repeat 1-5, but this time select red 'director' and the green will also show to select director account. repeat for each account.

I hope this action works for you by removing all the threading.

In my case, I did not suffer the same issue. I only had one folder set up to use threading by choice. Even so, I have found that procedure did not change that folder, so there is a bug lurking.

I would appreciate it if you could report back on what occurs after following the above.

Yes absolutely a BUG and a MAJOR BUG!

I have tried those steps probably a dozen times now and also same thing it does NOTHING!

Even the menu way choose un thread and Nope it is stuck.

really SUCKS!!!!!

re :Even the menu way choose un thread

I presume you did this:

• Select the Inbox folder
• Select an email in Inbox to get focus on the message list
• Set 'View' > 'Sort by' > select 'unthreaded'

And the threading did not switch off in the selected folder?

Please try using the 'Troubleshoot Mode' 'Help' > 'Troubleshoot Mode' In pop up - click on 'Restart' Another small window - click on 'Continue in Troubleshoot Mode' Thunderbird auto starts in Troubleshoot Mode. Then try:

• Select the Inbox folder
• Select an email in Inbox to get focus on the message list
• Set 'View' > 'Sort by' > select 'unthreaded'

Did it switch off the threading in that folder message list?

If yes: Try this:

1. In the Message List view, in the column header, on the far right, open the options button that shows context menu.
2. "Apply current view to..."
3. "Folder and its children..."
4. Hover over an account - Select the top red nss account
5. In the next menu select 'Inbox'

Did this switch off all the threading in all the Inbox subfolders?

If it gets rid of the threading then it would be useful to know. Also let us know what addon extensions you are using.

No Extentions at all.

But at LEAST This does work on ONE folder at a Time.

At least It CAN be fixed. I'll just have to do each folder as I come across them.

You fix the main folder and it gets fixed but sub folders in that folder stay threaded. so they have to be un threaded too one at a time.

Joe

Puzzling. When I follow the procedure, clicking accountname at the end, I get the message shown in attached screenshot, where account name was USANET. I had previously reset all manually to threaded and after going through the recommend steps, they were all unthreaded. I did not select inbox, but the account itself. The steps are tricky, I agree, and it took me a few tries to get it right.

Duh! I forgot the attachment.

Yup saw that message a LOT also. but never made a change weird huh?

Yes absolutely a BUG and a MAJOR BUG!

A bug was reported a couple of days ago: https://bugzilla.mozilla.org/show_bug.cgi?id=1801941.