I know how important it can be to be able to change the WiFi of your WiFi signal to avoid interference issues that can weaken your overall WiFi signal.
It is strange that you have been unable to change the WiFi channel via the Admin settings. I was able to adjust mine without issue. Can you try using a different browser to see if the issue is persistent? You should be able to toggle the radial button between automatic and manual. When the manual is selected the dropdown list for channel selection becomes active.
Can you also try to complete the WiFi channel change via the Ignite WiFi Hub App for Android and iOS devices? Once you are logged into the App navigate to the Network tab at the bottom, then select Advanced Settings, then select 2.4 and 5GHz WiFi. Please try to edit the WiFi channel here.