Z.com will obtain the WHOIS information from the losing registrar during the domain transfer process. However, if you notice that the WHOIS information is inaccurate after the domain has been successfully transferred to Z.com, it is due to the different notation format of the registrar. For example, the address field is filled with the phone number or organization name instead.
WHOIS information cannot be modified on the customer’s end during the domain transfer process. However, once the domain transfer is completed, you can make the required changes directly through your Z.com account.
You may refer here for a guide on changing your domain contact information.