Usage Limit not working

Hi there, under “Usage Limits” there’s a box that says “Usage limit per coupon”. I put 10 in that box.

I have discovered that this has allowed the coupon to be used on 10 orders. But, on some orders they’re buying multiple products.

I want the coupon to apply to 10 products in total across all users.

So if various users order something like this:

Order 1 – buys 2 products using the coupon

Order 2 buys – 8 products using the coupon

I want the coupon to now be void (2+8=10).

However, it seems that current there can be 10 orders, with the coupon applying to many more products than I intended.

How do I configure it to apply to only 10 products in total, across all users, before it is voided?