Under the General section of Global Styles, there's only one option (Fig 1): 

• Left Justify Campaign: When toggled on, this left justifies all the content in your email campaign. Toggling this off resets it to the defaults. 

Fig 1

To learn more about the other sections within Global Options, read the corresponding article: 

• Global Styles - Colors
• Global Styles- Typography
• Global Styles - Spacing
• Global Styles - Mobile Alignment