How to fix a single use discount applying to multiple items?

[Vickilh]

I am currently running a coupon for a percentage off one item to encourage new users to my webstore . I set the discount to be used only once but A buyer bought 2 items and it discounted both at the discount price  off . What am I doing wrong? 

[Vickilh]

I replaced the discount with a buy/get discount and that allowed me the control I needed to limit to one use, one item