1. Select 'Menu app icon' > 'Account Settings'
  2. Select mail account name in left Pane
  3. Bottom right: click on 'Edit SMTP server'
  4. Set outgoing server (SMTP) 'Authentication Method' to 'Oauth2'
  5. Click on 'OK'
  6. Select 'Server Settings' for mail account
  7. Set incoming server 'Authentication Method' to 'Oauth2'
  8. Click on 'OK' 

Last year Yahoo decided it needed better security. Mainly I use my PC (Windoows 10) or phone (Android) for email but now I have been asked to use the laptop again. According to my research the solution is to use SMTP settings of OAuth2 viz "update the Authentication Method' for the Pop or Imap mail account. 1. Select 'Menu app icon' > 'Account Settings' 2. Select mail account name in left Pane 3. Bottom right: click on 'Edit SMTP server' 4. Set outgoing server (SMTP) 'Authentication Method' to 'Oauth2' 5. Click on 'OK' 6. Select 'Server Settings' for mail account 7. Set incoming server 'Authentication Method' to 'Oauth2' 8. Click on 'OK' Exit Thunderbird Wait a few moments for background process to complete Start Thunderbird" Items 1 and 2 successful. Item 3 non-existant. Bottom right "Outgoing server (SMTP)" is set to Yahoo! mail smtp.mail.yahoo.com; there is no OAuth2 option. Further down on left is an option "Outgoing server smtp" but that opens the same windows as at bottom right. Question: where do I find the option to set OAuth2 please. TIA Anne