The old system was confusing for new users, especially since dotfiles are hidden by the OS by default. I've instead moved to using a JSON-based system. Should hopefully be much easier.
The new config exists in config/default.json. You can edit the relevant keys in there directly, or make a copy of it named local.json which is ignored by git so you don't accidentally commit it.
If you were previously using .env to configure your server, a script will try to upgrade you to the new system and add a local.json file for you with your previous configuration. If it does so successfully, please update the .env file and remove the CP settings (and leave the rest there!) so the script doesn't have to run again.