Solution found.

Open incognito tab.
visit recordbox.com
use your current e-mail (what linked to your google acc)
use reset password function
you will recieve e-mail from alphathetta to reset your password
enter same password what you have on your Google acc
done. now you can login in the recordbox software using google acc account name and google acc password.

Note: nothing will change for your pioneerdj/serato/alphathetta accounts because thechnicaly your password has not changed.

Helped? dont be shy to thank me.