There was what, 4 weeks, between V145 and 146 as Thunderbird is not on a 4 weekly release schedule. I see nothing in the release notes for V146 that would constitute anything like the changes you refer to. So I am stuck because I have no idea what it is you do not like so I can tell you how to change it and I have even less Idea what version of Thunderbird you were using before the update. But as 145 was released on November 13, 2025 I do not think you have been using it since "all my life" or even for more than a couple of months really.

So what is the actual problem? My Thunderbird looks much like it did when V3 was released in 2009, apart from having a serious lack of color for the toolbars. I still have the three pane view of my mail I had when using version2 with essentially the same lists. Everything has been replaced and someone thought a multi line mail list would be good. I hated it when it came out and I still see it as a space waster that offers me nothing but aggravation, but it took about two clicks to get back to my old list view so I am not really bothered, except I had to make those clicks.

Here is a link to the Thunderbird releases archive. It has every official release of Thunderbird that has ever been made and for each of the supported operating systems. I am not trying to hide the information, I just think you would be better of not using it. https://ftp.mozilla.org/pub/thunderbird/releases/

You state you lack patience and an attempting to revert to a previous version would require a reasonably steep learning curve and patience. So lets just fix up what you have if we can.

> I donated 194 SEK on December 26th when I downloaded the program. (And it wasn't the first time.)

Thank you for your donation.

I agree with Matt, but I also wonder why you had to download the program again, and you say this wasn't even the first time? You have been getting some type of error that causes you to download again?

Thank you both for your quick replies and for taking the time to help me. I had a feeling I was going to mess up the version information. The version numbers I presented are apparently the version numbers of the exe-files for Thunderbird.( I got V 145 from properties in a previous backup.)

Describing why I reinstalled Thunderbird would be too long. So I'll obstain from that. Thanks, Matt, for the link to the releases. I'll follow your advice and not use it. To Wayne Mery, I'd like to say that "And it wasn't the first time" refers to donation and nothing else.

I'll start from the beginning. The version I have on my PC right now is this:

Thunderbird Desktop Version 140.4.0esr | Released October 14, 2025

I want the installation file for Thunderbird win64/sv-SE that I had before. For obvious reasons, I don't know which one it was. I hope you can identify it.

Best regards Hans Peter

I am sorry I so not know enough to support Thunderbird downloaded from the Microsoft store. Perhaps Wayne can help you. I have no real understanding how the MSIX version works or where it stores it's data. It apparently "depends" but I have been unable to determine exactly on what. What the sandbox means in use and how that version decides where to store data and when to use existing profiles and when to start all over again.

Perhaps Wayne can assist you with it. The team released that version be there is no documentation at all about what the special Microsoft MSIX environment means. I did once try via bug reports to determine what happens. I learned very little in many hours of searching and gave up.

Hans Peter, we have no way of knowing what you had previously installed. You might check Windows Settings > Installed Programs (or something like that).

I'll repeat an earlier question - what do you think has changed?

Thanks, Wayne Mery, for your interest. I'll answer the question first. So much water has flowed under the bridges, so I don't actually remember what didn't appeal to me. I also had trouble with Mailwasher and the start of Windows at the same time so the chaos was great. Currently I'm running Thunderbird 140.6.0esr (64-bit) and trying to reconcile myself with it. I've checked my backups and found this:

Which of the folders in these profiles contains the version number, do you think? /hans peter

If you first installed Thunderbird in September, then you likely installed 143.0 https://www.thunderbird.net/en-US/thunderbird/143.0/releasenotes/ and not https://www.thunderbird.net/en-US/thunderbird/140.3.0esr/releasenotes/.

compatability.ini in the Profiles folder may show an older version number - do not edit that file. xxxxx.default-release is probably the profile you are currently using. xxxx.default is normally unused.