How to Transfer ONE OF FOUR Thunderbird PROFILES to a New PC

I think what you're calling a profile is really an account. If the account you want to install on the notebook is an IMAP account, you could just add it to TB on that computer and the mail folders would synchronize with the IMAP server. Otherwise, since TB doesn't have the option to export and import individual account data, you could [https://support.mozilla.org/en-US/kb/moving-thunderbird-data-to-a-new-computer transfer the Thunderbird folder] from the desktop to the notebook, and then on the latter set the desired account as the default, and then Remove the other three. The last two steps are done through Tools/Account Settings, Account Actions at the bottom of the left pane.