Global Styles are set up in your Site Settings. These centralized settings are applied across your site for a consistent design. 

You can access Site Settings from any Page or Template. We recommend going to your Style Guide Template so that you can see many examples of typography and widgets changing. Once on your chosen Template, click Settings > Site Settings.

Once here, you can open and close each Menu item to make changes.

There is a template that cannot be deleted without losing all your site's style information. This is noted as DO NOT DELETE in the title.

To learn more, check out this Elementor Article: Theme Style Global Settings.