If it is reordered when done, but reverts when restarted, that is an indication that thunderbird is being prevented from updating settings at shut down. That is usually caused by a VPN or an anti-virus attempting interference. If you use an antivirus other than the default Windows antivirus, or a VPN, please adjust settings to bypass email checking. you can sometimes verify this by seeing if there is more than one prefs.js in the profile (such a prefs-1.js, prefs-2.js). click help>troubleshootinginformation, scroll to 'profile folder', click 'open folder'. You will now be in the profile. Is there just one prefs.js there?

Thank you David for support. Actually when I change order in Account Settings, close the tab and re-open I see it reverted (without closing TB). When i checked Profile Folder there are several prefs.js files (prefs, prefs-1, ..prefs-3.js) but pref-x files are very old dated. pref.js is new. I tried to close protection in ESET and tried again but it was same.

Thanks

If I understand, you change order of accounts, close the account settings pane, then reopen the account settings pane, and the order is as it was before, all without shutting thunderbird down. That feature works on my 146, so my first suggestion is to restart in troubleshoot mode and see if the reorder works then. That might indicate an addon interfering.

I tried troubleshoot mode but same. I upgraded from 142 to 146. May be my installation is not good. Thank you for support.

It is very likely something minor, but I am not seeing it. But, I'm not the sharpest tool in the shed. I will see if I can locate someone with more expertise who might see the issue.

Try this: Help/Troubleshooting Info, Profile Folder, Open Folder, close TB, delete or rename folderTree.json, restart TB, see if the account order in the Folder Pane retains edits.