The credentials that you provide in the Domain Logon dialog are not the credentials with which you log in to Adaxes. When you register a domain in Adaxes, you provide administrative credentials to perform operations in the domain. Any operations performed via Adaxes in that specific domain by any user will be performed using the administrative credentials that you provided.
The credentials that you provide when logging in to Adaxes (either when logging in to Adaxes Web Interface or when authenticating in Adaxes service in the Administration Console) will be used to authenticate you and properly apply all the security restrictions imposed on you via Security Roles etc. For more information, see Technical Overview.
Thus, when you change the credentials in the Domain Logon dialog, you change the administrative credentials for your AD domain, that is, the credentials used by Adaxes to perform operations in the domain. For information on how to log in to Adaxes service with alternate credentials, see the following help article: http://www.adaxes.com/help/?HowDoI.Mana ... count.html.