Hey Ben,Are you a plus customer?Also, can you provide the store link so I can better see the ui/ux.We might be able to help with hiding and showing certain payment options on your checkout.Thanks!

I asked my team members and they faced this issue.Here's his reply – "Shopify takes a random product to checkout to give preview and show edits. That product should be in stock, - that's a quick fix. Or you can change that product by clicking preview...

I am unable to understand what specific element you want to change. Please provide a screenshot. I think I can help with this.