I'm working on a client project using Shopify.
There are two things we need to be able to do:
1) Change the words "Sold Out" to "Out of Stock" when an item is out.
2) Have the Quantity custom to the product because many of our products are sold in cases of 2, 4, 6, etc. We want the default quantity to be 2 (or 4 or 6 depending on product) with increments of that.
This thread is quite old, but if this helps others who are looking for the same solution for selling in incremental quantity like 2, 4, 8, 24, 100, 500, etc.
You can use the MultiVariants ‑ Bulk Order app for incremental quantity selector (dropdown). You can list all your available quantity ranges and the app will convert the default input box into a dropdown in the product page as well as in the cart page to edit/update quantity from the available range.
Here is the demo, you can take a look.