This usually means something is interfering with Thunderbird's update of settings at shutdown. This might be an antivirus product or other firewall issue. This can often be verified by clicking help>troubleshootinginformation, scroll to 'profile folder' and click 'open folder.' the settings file is named prefs.js. If you see more than one, such as prefs-1.js, prefs-2.js, that is an indication of the problem. This occasionally happens when prefs.js is marked read-only. I do not know the solution for your particular situation. This may not be your problem, but it does show the same symptoms.

I looked in my profile and noticed that there were three (3) extra "prefs-{n}.js" files. I deleted them, because they all had much older "Date Modified" dates in Windows than the "prefs.js" file whose date was today, then closed Thunderbird. I reopened Thunderbird and looked at my IMAP inbox email listing and it had changed. My column headings are: Thread, Starred, Attachments (very narrow), Subject (wide), Read Status (very narrow), From (not quite as wide as subject), Spam (very narrow), Date (wide enough to display date and time), and size (wide enough to display size). I sized them the way I wanted then applied them to some of my local folders. I'll readjust the columns, assign them to other folders and see how that works.

Thanks for your help.

Bill

You're welcome. I hope all works out well.

David, the thread pane column widths are not stored in the prefs.js file but in the xulstore.json file (image)

Mapenzi, THANK YOU. I know little about the json files. I appreciate your sharing this.

I only have one of those.

I only have one of those.

Which are "those"?

"Which are "those"?"

An "xulstore.json" file.

I think this is a little derailed.

The xulstore.json stores information related to the calendar interface. Data about the various column in mail folders is stored in the relevant MSF files (One per folder).

I started this to ask if those files are being updated at all and it is still relevant. It can be that repairing a folder or building a new index post compact can also changes some things in unintended ways. The more the developers tinker with their new message database, the more of these odd glitches I think we may see (in the end there will be no MSF files is my understanding. But as of now they are a critical component of showing you your mail lists.

MSF files update on new mail, compacting changing read status etc. So what I am asking really is for you to look for a common denominator. Perhaps a compact of a folder that has had much mail moved out of it or deleted might be the trigger for the change. It might be only folders that have had mail that has triggered some sort of virus alert.

Thanks! Contrary to more than 400 prefs-(nnn).js files in a French Mozilla forum user's Thunderbird profile I have never seen more then one xulstore.json file in one profile. I propose that - TB closed - you rename the xulstore.json to xulstore.json-old, then restart TB. On restart you will have a rather strange view of the Thunderbird main window and its different panes since all height and width settings will be default and not your usual customisation. That's why you should not delete your xulstore.json file as a first step, so you can always go back.

Now customise the choice of your thread pane columns to be displayed and their respective width, quit and restart TB and verify if columns and widths have been memorised.

You can also install the "DefaultColumns" add-on https://www.ggbs.de/extensions/DefaultColumns.html which permits to save your columns customisation "as default", so they will b applied in all other folders (image)

Okay. This isn't fixed. It started with some recent version of Thunderbird. It is so exasperating to have to constantly deal with changes to the Thunderbird interface depending on which version I have. I've done everything suggested in the Thunderbird and Internet forums and it still happens.

When I fix the unrequested change it works fine within the subfolders in an explorer folder, but not other folders, until I physically change them ...AGAIN... It seems the change lasts as long as TB is open.

I'd so much like to resolve this as I rely heavily on what I can see with the columns I have chosen.  :-(

I still have my original suggestion on this, that something is preventing Thunderbird from updating at shutdown. If all seems well after a change, but reverts when restarted, that seems the issue to pursue.

Hi Bill, just let's make a step back to the basics of saving customised columns since in my understanding this is not intuitive. Did you save your modifications each time via Apply columns to > Folder and its children > select account in which you want to apply your choice > click account (and not on one of its folders; see my image) Did you test the add-on "Default Columns" I mentioned in an earlier reply?

David - the "prefs_{n}.js" files were deleted after your suggestion, and that seemed to work for a while. But now this pesky problem is back (almost immediately).

Mapenzi - I figured this out after a few failures (it really isn't intuitive). What I normally do is simply drag the column width to the correct width (which is also very funky in that dragging one column width mostly widens other column widths - it's very weird because sometimes you have to drag several column widths to get the correct column to the correct width) then right-click a column heading and navigate to the "apply columns to...". The worst part of this is when the column widths go haywire I have to run through this process all over again for all of the big folders and custom subfolders I have, which are a lot! Sigh...

I wish Thunderbird would fix this because the problem occurred sometime after the complete re-write of v102(?) and I'm up to 140.7.1esr (32bit). I do run Thunderbird as a portable application for obvious reasons, including the "Data" folder is on an NAS drive that is backed up every night.

One more thing. Mapenzi - no I did not test the add-on "Default Columns". I'll give it a try today.

I just closed TB and reopened it and most of the column widths were messed up again. Sigh... I'll install the add-on and see if that helps.

I just closed TB and reopened it and most of the column widths were messed up again.

In previous TB versions sometimes I encountered this issue, too. Actually I cannot reproduce this behaviour neither in TB 140 esr nor in TB 147 release

Well, shutting down TB and reopening continues to alter the column widths. The available add-ons "Set Default Columns" and "ColumnsWizard" do not work with v140 of TB.  :-(

The internet seems to say this is a problem with Thunderbird that isn't fixed.  :-(

Well, shutting down TB and reopening continues to alter the column widths. The available add-ons "Set Default Columns" and "ColumnsWizard" do not work with v140 of TB.  :-(

OK, my bad! I have installed "Default Columns" in my v140 esr profile but it seems that it doesn't save columns widths but only which columns are active.

The internet seems to say this is a problem with Thunderbird that isn't fixed.  :-(

Source ..... ?

OK, I may be totally wrong, but I suggest changing something else in Thunderbird, such as changing compose option from HTML to plain text, change threading for a folder, change tableview/cardview - shutting down and restarting. If those items reflect the change, then my idea is wrong. I wish you well, regardless.