You will find info on resetting your primary password here: http://kb.mozillazine.org/Master_password And Google has no argument with Thunderbird; it treats all third-party software the same. The requirement for the Oauth2 authentication is not specific to Thunderbird. In resetting your primary password, all passwords to your accounts will be removed.

Thanks very much, but that doesn't solve my problem. I have no primary password (and don't want a primary password) It is just the (secondary?) password that doesn't work - that is the one I want to reset.

Go to tools>settings>privacy&security and click 'saved passwords' to show and then rightclick on the desired row and a menu will open with an edit option.

I tried that a few days ago. Tools leads to Account Settings but there is no Privacy & Security option I never saved (or even save) my passwords but I do write (type) them on paper The password I recorded is not accepted on my new computer (my old and normal machine) has no problem and I have been using this for several years without having to re-enter the password.

Options: Tools > Address Book Saved Files; Add-ons and Themes; Activity Manager Import; OpenPGP Key Manager; Developer Tools; Clear Recent History Account Settings; Preferences

Preferences leads to Passwords which shows Saved Passwords and "Use a Primary Password" but no option to reset a password

At Preferences and passwords, you must highlight the row for that account, then right-click to see a menu to change the password. You would need to do that for both rows (input and smtp servers).

At Preferences and passwords, all I find is:

• Passwords
• Thunderbird can remember passwords for all of your accounts. (Box) Saved Passwords...
• A Primary Password protects all you passwords, but you must enter it once per session.
• (Box) Use a Primary Password

As I have said I don't have/want/use a Primary Password

Am I using an old version of Thunderbird which is no longer supported, but works very well on my old desktop computer? I can't install it on a new computer (Linux) or a laptop (HP or Lenovo) without the password and I can't change the password or even reset it.

Click the box 'saved passwords' . click to show passwords. then highlight the row of the account and rightclick.

That doesn't help because I didn't save that password.

Since I wrote the password on paper and haven't changed it since, I wonder if the problem is not the password but the wrong configuration. I am using IMAP Configuration:

  Incomoing : imap.dreamhost.com SSL/TLS
  Outgoing :   smpt.dreamhost.com SSL/TLS

and my username is correct

I am confused. You state that Thunderbird does not have the password, nor do you. So continuing to search Thunderbird is fruitless. Generally, if you are receiving a message of incorrect password, that is the reason. However, if you post screenshots of incoming server setting and smtp server setting, someone here may see a possible error in setup.