Well, you could set up one profile with all of the accounts and then copy to the other PCs. After installing on one PC, do a backup of the proflle and then restore on each of the others.

BACKUP

1. ensure thunderbird is not running
2. enter %appdata% in search window on task bar and press Enter key
3. this should open windows file explorer in Appdata\roaming folder
4. highlight the Thunderbird folder and copy to external media

RESTORE

1. ensure thunderbird is installed and NOT running
2. enter %appdata% in search window on task bar and press Enter key
3. you should be in Appdata\roaming folder , copy&paste the exported Thunderbird folder there. This will prompt to overwrite an existing folder of same name. allow it
4. start thunderbird and all should be there

Thank you for the great suggestion. That solution will work if both Thunderbird accounts are at the same revision. So it's best to bring both applications to the latest rev. Then copy and paste the Thunderbird folder. Also, the copy process took a loooong time when copied onto a USB memory stick. Other than that it worked great.

I am glad all is well. To clarify, this also works with receiving PC is at a higher level, but not too far apart. That is, going from 115 to 140 would not be a problem, but going from version 60 would be. That is because many updates happened that would require manual intervention. Also, if the long copy was due to copying large IMAP accounts, those message folders can be deleted (with thunderbird NOT running) to make the copy faster and with fewer resources.