Unable to change DNS, router NOT in AP mode.

Howdy folks. Some background: Set up Orbi network this morning from scratch (long story, sons wanted to stay up later playing Overwatch, so.. yeah).  Anyway, part of the process on initial setup is to check and update firmware.  I'm now on V2.3.5.26 and now there is a new "A Security" chicklet on main admin page.

I am fond of using alternate DNS services (mostly to avoid the outages we've seen from my ISP DNS services).  Under Advanced > Internet Setup, "Get Automatically from ISP" is the only option. I am no longer able to input alternate DNS server IP addresses. The option to "Use These DNS Servers" is greyed out.

How can I input OpenDNS, 1.1.1.1 or Google DNS?