Cashier attendant didn’t helpful or advised customer about digital

First time walking to this store to buy a pork shoulder that was on sale with a digital coupon. My wife registers the Von’sAlbert-son app to download the coupon with a QR code. Upon walking to this cashier I show her the QR code off of the phone, she replies what is this, she doesn’t know to try to explain to her their sale for type meat and the worst funny part is, she has the store weekly ad in front of her. My feeling is she doesn’t want to do it or maybe is the stored closing time..So with my ignorant low-level education, I left the store confused and angry …I didn’t catch her name but from the donkey face(old Asian lady) I think she is the stored manager. when I got home I figure out what was wrong I didn’t realize I download Von’s app instead of the Albert-son app. My wife told me there was the same company. Well, I guess not ..Tomorrow I will go to a different store. I feel that the employee, even the store manager should be educated to help people with digital coupon (QR code) understanding. People like me 50 some years are very slow to understand QR code, Different app for Von’s and Albert son ..from my personal understanding the old Asian lady is not a manager you should downgrade to grocery baggier instead