With Extras --> Export you can export all your Thunderbird settings (accounts, addressbooks, mails) to a .zip file to backup it or to move it to another computer.
The problem is: if your profile folder is greater than 2GB it is not recommended to do it this way.
There is no way to only export all your account settings and passwords, but not all local stored mails.
It would be great, if the user could choose via some checkboxes which data he wants to export, so you can deselect "mails" and only export account settings etc.