The YAML files allow you to edit your server settings.
They can be found in the
config directory in your server installation.
After modifying your configuration files, you will need to restart your server to apply the changes.
If you want the server to simply generate/validate configuration files without starting the server, you can use the
--generate-config command-line argument.
Simply add the argument at the end of the
java [...] -jar glowstone.jar line inside your startup script.