The one positioned at the top of the list is the one that is set as default.

You can change which account you want to be set as default.

• Right click on a mail account name in Folder Pane and select 'Settings'

Account Settings window opens.

• Select the account name which you want to be at the top.
• click on 'Account Actions'
• Select 'Set as default'
• click on 'OK'

see image below as guide.

hi, thanks for your reply, unfortunately that doesnt solve the problem, indeed it moves that particular account to the top but only in that settings section, not in the default screen of thunderbird, there it stays the same as before changing default account

The default account should move to the top of the Folder Pane after a TB restart. To sort the accounts in any order, there is an add-on:

https://addons.thunderbird.net/en-US/thunderbird/addon/manually-sort-folders/

https://support.mozilla.org/en-US/kb/installing-addon-thunderbird

after installing that add-on, the default e-mail box which was set as default, went to the top, and it stays there even if I switch it off, I didnt even have to manually in that plugin settings put it to the top, so it somehow "fixed" that bug, and with that plugin I was able to change order of another e-mail box in that left menu,

thanks again for help!