Cannot access WHM

Hello I am new here, so I am creating my first website recently and I can access cPanel, but I need to make some changes related to my domains, basically I want to change the primary domain and see the backend settings with my other domain, because when I try to access the second website I got the error " DNS_PROBE_FINISHED_NXDOMAIN". Everything seems to be fine. So I need to look on the WHM side but unfortunately I don't have the credentials to access / never set up a credential. I've tried with the same credential as I have access to cPanel, but it shows as incorrect. How can I resolve this situation