Config.set a custom value for all platforms

I’m trying to set a value (for ex. my API URL) in Config for all platforms.
this.config.set('', 'url', 'http://localhost/cpapi/public'); console.log(this.config.get('url'));
I run the app on browser by running ionic serve in terminal, get null in console. Am I doing it wrong?

I have the same problem? Any solution arround?

I just saved it without the first parameter…
And then I get the token back from the config.
For me it works in that case.

          this.config.set('myToken', token);
'token from the config', this.config.get('myToken'));