Can't access global variable from other files in Node JS

I'm trying to access my config.js file in all modules of my project but I can't even though the config file is defined as global.

Here's my packaging:

in the server.js I have defined:

global.config = require('./app/config');

I can access the properties of config in server.js but when I try to use config in other files such as user.js I get this error:

config is not defined

I don't know how to fix the way I'm defining this global variable.