Keychain- again

When I change a password (on the site it applies to), Keychain ALWAYS remembers the 'old' password. Is this expected behaviour?

Surely Keychain SHOULD immediately update all passwords?

Example- online bank accounts always return "wrong password" when accepting the stored password; then I can enter the correct/new one, no problem.

Keychain tries to remember every password you've ever entered for a site. In the case of a site where you had an old password and now have a new one, you can edit the Keychain entry in the Keychain Access app. Sometimes I've seen Keychain create a "new" entry for the same site, thus ending up with multiple entries. Again, you can edit this pretty easily with Keychain Access.

Thanks Chas

And as a suggestion, do not keep banking passwords in Keychain.

For security enter each and every time.