If you have multiple users on a machine, create a separate Windows user account for each person.The Keepass Helper add-on 'Adds a hostname, URL, or email account ID to the application's window name (e.g., that of Firefox or Thunderbird) to make it recognizable to password manager utilities like KeePassXC.' KeeBird is a alternative that explicitly supports version 60.*. Another solution would be to use a free password manager that can auto-type passwords such as KeePassXC. Its not very strong, but is secure enough to deter most casual snoopers, especially if you use a long password.

If you configure one it will prompt the user for a master password when they run Thunderbird. The master password is meant to protect your stored passwords, not your profile.This method may be sufficient if other people accessing the same computer are not technical or if they are unlikely to deliberately snoop. It is trivial to bypass by running in safe mode (to disable the extension) or by using a text editor such as Notepad to read the text files that Thunderbird stores the messages in. The ProfilePassword extension requires a user to enter a password in order to use the profile.

Encrypt contents to secure data