Can't change my DNS with Pihole installed?

I just realized that pi-hole locks my odroid C2’s DNS to Is there any way to have pi-hole but not use it for my device, just devices connected to it? I use my VPN on my odroid as well and am trying to fix the DNS leak.

Also, where’s boot.ini file referenced here so I can change the max CPU frequency? I want to figure out if it can go higher with proper cooling. Are there any ram oc settings implemented in DietPi? I probably won’t bother with ram though.