I tried to setup a new DNS but the options got me so confused, So could you help me please?
How to setup Quad9 or any private dns in PersonalDNS-Filter app? (Android)
I have downloaded the app and it confuses me as well. If you are in Android 9 or higher, you can setup DNS-over-TLS on your phone via the settings (you can setup Quad9 and others via this setting). If you want to block ads, trackers and other domains via DNS, then NextDNS is good.