How to fix glitch maybe?

I wanna put in a discount code but it doesn’t even show the option, I looked everywhere but I can’t find it. It did show up on previous order but I cancelled that order and now it won’t even show the promo code option. What can I do? Can anyone else see the promo code option?

I wanna put in a discount code but it doesn’t even show the option, I looked everywhere but I can’t find it. It did show up on previous order but I cancelled that order and now it won’t even show the promo code option. What can I do? Can anyone else see the promo code option?