STEP 1
Access your Shopify Admin's Theme Library to open the theme customizer.
STEP 2
Go to the Top Bar, and click on the Template picker.
Click Collections, then Default collections.
STEP 3
Scroll down to Templates, and click on Page content.
STEP 4
To change your layout settings, select 'Container size' and choose 'Default' or 'Fluid' for the width.
Important:'Default' follows the page width set on Theme Settings > Advanced settings > Page Width (1180px by default).
STEP 5
Click Save.