Unable to revert DNS back to "GET AUTOMATICALLY FROM ISP" setting

Router is RBR750 ??? (RBK753, purchased June 2020 at Costco). Could not find in MODEL dropdown.

Good day,

Due to lacking parental controls and security for bad websites, I decided to maybe tone down risk by using OpenDNS (Cisco 208.67.222.222) to do some filtering.

As I have been getting some recurrent "page not found" using Chrome... only to finally get the page open 2 or 3 seconds after, I decided to revert to using ISP's DNS but found I am unable to set back default in "ADVANCED>INTERNET SETUP>DOMAIN NAME SERVER settings... unable to click back on "GET AUTOMATICALLY FROM ISP".

The router is RBR750 (RBK753, purchased June 2020 at Costco).

Netgear support did not provide explanation or solution (other than the good old "why don't we reset to factory settings?")... L1 checked with L2... no solution.

Anyone with same issue?