To find the configuration file for Teeworlds, you can read this guide. If you want to configure the client, check out Client Settings. If you want to find the client commands available, see Client Commands. The client configuration file is located in different locations depending on the operating system.
Run the file called config_directory.bat, that can be find in the Teeworlds directory, or enter directly
%APPDATA%\Teeworlds
in an explorer window.
The config file is located in ~/.teeworlds
The config file is located in ~/Library/Application Support/Teeworlds