Firefox browser natively supports DNS-Over-HTTPs. Let's configure ControlD on it.
Go to "Preferences" (or Options) in the top right menu button.
In the “General” tab, scroll down to “Network Settings” and click on “Settings”
Select “Enable DNS over HTTPS” and choose “Custom” under “User Provider”
Input the DNS-Over-HTTPS URL into the field. If you're configuring our free DNS resolvers, you can use these:
If you are configuring a custom DNS resolver, you can find your DoH URL in the My Account section.
Go to "about:config" in the address bar and click Accept.
network.trr.mode to 3.