Retina v5 introduced advanced options for variant selection, management, and appearance.
Use the Products portion of the Theme Settings to automatically select the first available variant or prompt customers to choose a variant (no default selection), then select a sold-out display option for your variants.
Automatically select the first available variant
By default, the Auto-select first available variant setting is enabled. This allows customers to either add the default selection or select another variant before adding it to their cart.
Prompt customers to choose a variant (no default selection)
Click to disable the Auto-select first available variant setting to have no default selection. Instead, customers are prompted to choose from the available options before adding the variant to their cart.
Select a sold-out display option
When variants are sold out/out of stock, they can be concealed, visible but disabled, or visible and selectable.
Use the Hidden option to conceal out-of-stock variants.
Use the Disabled option to keep out-of-stock variants visible but not selectable by customers.
Use the Selectable option to keep out-of-stock variants visible and selectable by customers. While the variants are selectable with this option, they cannot be added to the cart.
This feature is often a requirement for 3rd-party apps for back-in-stock notifications.