Looking to access your theme's code or language options with Shopify's new theme editor layout?
In your Shopify admin click on Online store > Themes
Next to the theme that you want to edit click on the Menu button which is a small square with 3 blue dots
This will open a submenu of options which includes: Edit HTMl / CSS and Edit Language
In your store admin click on Settings > Checkout
In here you will see the customer account options to enable these and make them mandatory if needed.
Your theme will then show the customer accounts options at the top of your site.