Is there a problem?

not settled yet.

The support.mozilla.org accounts is separate from the Firefox Accounts system.

Is the problem with many websites, some, a few?

Have you checked the stored password? Type about:preferences#security<enter> in the address bar. Look under Logins,

Note: For Firefox 56+ its; about:preferences#privacy Look under Forms & Passwords +++++++++++++++++++++++++++++++ Turn on Remember Logins. To check the passwords you have listed, press Saved Logins.

Press the Exceptions button and see what's inside.

https://support.mozilla.org/en-US/kb/usernames-and-passwords-are-not-saved Usernames and passwords are not saved

https://support.mozilla.org/en-US/kb/fix-login-issues-on-websites-require-passwords Fix login issues on websites that require a username and password

James said

The support.mozilla.org accounts is separate from the Firefox Accounts system.

Dear Support team,

Greatly appreciate your soonest and patient reply. Actually the user name for log in to Firefox support community should be not email address. I forgot to key in user name preset instead of the said email address. Now it’s ok.

Best Rgds Kurt Pan