Panoramic Modem / Router - DNS Server?

Is it not possible to change the DNS server on a panoramic modem / router (CGM4140COM)  from the assigned cox provided one to one like 8.8.8.8 (google), 1.1.1.1 (Cloudflare)?

There are already so many limitations with this device that it is an insult to be forced to pay for it when one already owns one's own modem and router that works fine and was previously provisioned to work with my Cox account. The only thing we changed was added telephone services and have ended up with junk hardware as a result.