@enoter You do not need to edit core files in Ghost to do this - and this is really terrible advice to be giving out. Editing core files means the configuration would go away on every update, and we publish a new version at least 1x per week.
@Morven_Huang Assuming you installed with ghost-cli you’d run ghost config url <your domain here> and then ghost restart to change the domain. If you need to get nginx configured run ghost setup nginx ssl and the cli will ensure that nginx and ssl certs are correctly created and configured for you.
If you didn’t install with Ghost CLI, you should manually create your own configuration file in your Ghost root: https://docs.ghost.org/docs/config#section-custom-configuration-files