One of the leading open-source cross-platform email clients, Thunderbird allows you to manage email, news feeds, chat, and news groups. To resolve a problem of change password thunderbird, you can navigate to Tools > Options > Security > Passwords, and then click on Saved Passwords. If you click on Show Passwords, you can see the existing password; however, if you have forgotten the password, you need to reset it by following the on-screen prompts. Ensure that you have an alternate email address where you will receive the verification code that will be required to set a new Thunderbird password. Once you set a new password, your Thunderbird email password problem is resolved and you can use the new password for all the future logins.
Tools > Options > security > Passwords tab click on 'Saved Passwords' click on 'show Passwords'
There will be two lines - mailbox (incoming), smtp (outgoing) highlight these lines click on 'Remove' click on 'close' click on ok to save changes to options.
Close and reopen Thunderbird. It will prompt for password. Enter the same password you use to access the webmail account. select the option for password manager to remember the password and click on ok.