Okay, I know nothing of sendgrid, but this may help: - settings>privacy&security - click 'saved passwords' and 'show password's - the row for input and output should be visible. click the edit button to change password of the SMTP server setting.

ah this might work thanks!

When you set up an account automatically Thunderbird does not ask for a separate password and probably 99.9% of folks use a common password to receive and send.

Thunderbird can have as many outgoing SMTP server as you chooose for it to have. They are simple to add in the account settings > outgoing server (SMTP).

The choice of SMTP server to use is set in the identity part of the incoming server, that is the pane above the server settings in account settings. There is no practical limit to the number of identities that can be configured for a single account.

You ask why? surely you communicate with colleagues using a normal non web bug laden email server that does not attempt to report on every aspect of the recipients actions. You can have multiple identities, with multiple signatures on the same account so you can communicate with customers, colleagues and friends from the same account appropriately.

Passwords are as David pointed out stored in a password manager. However other than to occasionally go there to check what a password is and the delete entries I have never really had a use for the actual password manager edit options. I tend to delete existing entries and allow Thunderbird to request a new password rather than try and edit what is in the password manager. This habit has been reinforced as oAuth tokens are stored in the password manager and they can not be "changed" by the user, only deleted to allow the authentication flow to regenerate as required.