What browser you are using because you might click save password on your account when you sign in to your browser. Try go on the settings>save password and check for Bitcointalk.org account info. There’s no way to recover it using bitcointalk feature because it needs password to do any changes on your account settings. Your best chance is to check your browser if you save the data of your account when you login since browser always ask to save password the moment you login using the account that is still not saved.

It’s very unusual to forget the password right after you login but I do understand you if you are using too complex password.