By default, Thunderbird is set to automatically update itself but you can always do a manual update. Here's how:
Note: If you run Linux (such as Ubuntu) and use your Linux distribution's packaged version of Thunderbird, you will need to wait for an updated package to be released to its package repository. See Installing Thunderbird on LinuxThis article only applies if you installed Thunderbird manually (without using your distribution's package manager).
Go over to the Help menu and select About Thunderbird.On the menu bar click the Thunderbird menu and select About Thunderbird.At the top of the Thunderbird window click the Help menu and select About Thunderbird.
The About Thunderbird window will open and Thunderbird will begin checking for updates and downloading them automatically.
When the updates are ready to be installed, click Restart Thunderbird to Update.