I don't think you need to (or can) set the AD account on a DSN. The AD option uses a trusted connection, which is your account (or if the DSN is used from a service - such as QVS - the service account). So it is unnecessary to set the account because the account is determined by the calling context, not the DSN.
The options that are grayed out are for SQL Server authentication (and are not AD related).
If you cannot connect to the server, then you need to change the login permissions for the account on the SQL server.
Hope that helps