How do I turn off automatically managed settings on Gateway router

Sorry if this is double-posted, but it seems my question got cleared when I pressed post before. 

I would like to disable the automatically managed settings on the Gateway router. I understand that it uses WiFi Intelligence in order to determine the best settings for optimal performance. Unfortunately, it used its intelligence to select the most congested channel on 5ghz. If there is no way to turn it off, is there a way to test its Intelligence? Are there IQ tests that can be used by Xfinity to determine if my router is just unfortunately very dumb? Is it possible it's like me and just needs medication to get it to actually try? I can potentially share my medication with it but that may be an expensive route and I'm not sure of the legality of giving restricted medication to a wifi router.

If all this fails, and Xfinity is just saying the standard defaults are "automatically tuned" and there's no actual mechanism for changing it due to absolutely insane decisions (which I DOUBT SEVERELY!), can I just buy another router that is dumber and allows me to do stupid things like select my own channel like the idiot I am? Will I no longer get the unlimited data that I needed to buy this router to get (again, also probably a very good reason for this and not just an insane, arbitrary cost)?

Thanks!!!!!!