How can I prevent my clients from editing their invoices?
I'm trying to use Drupal Commerce to handle billing for my web design and hosting clients.
The problem is, my test user ("test client") can change the quantity of items in his cart, or even remove them altogether. Obviously I don't want to send people a bill and have them decide that no, they don't actually owe me for this month's service fee, and then proceed to remove it from their cart.
How can I make it so that only administrators (i.e. me) are allowed to add, remove, and change the quantity of items in a cart?