John Price I have no idea who told you that because this is a corporate wide discount.
You can sign up online https://www.lowes.com/mylowes/login?context=military or go to the customer service counter and they tie the discount to your MyLowes card so you will never need to show your ID again.
When you buy something and they scan your MyLowes card it subtracts the 10% automatically.
Something else I learned is that it WILL stack with any other discounts they offer. My Samsung Fridge was $4999 MSRP. During Labor day they offered 30% off that model. For Grins I scanned my card and they took an additional 10% off.
I would try the online way at a minimum if the local store is giving you any grief.
Thanks!