Just so you know, the forums don't use a different password than the geocaching.com website. They use the same username and password. There isn't anywhere in the forums where you can change your password. If your password works on geocaching.com, but not on the forums, you should email contact@geocaching.com to see if they can fix it, because there's definitely an error.
Well, I know that. The password is ok on geocaching.com but it just doesn't work here in the forum. I do have contacted the email address you mention but the proposed solutions didn't help. Maybe I should try again. Anyway, mentioning about the password issue was just to say that for PQ I had used a PM account; the one I signed my initial message on this thread. When writing this I see that the queries were generated correctly! Thanks again !