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
Customer accounts are a core feature of Shopify and are not theme dependant
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.