Why is WIC so hard?

Gosh why is Wic just so darn tricky?? Last week I took in a cheese and let somebody get Pepperjack when they should have gotten cheddar uckyyy! On another voucher somebody got whlole milk when they should have gotten lowfat good grief I don't want to get downgraded to bathroom only cleaner. I mean people probably already think I got fired from the pharmacy and Neil avoids me like the plague when I am on register so I don't want to get kicked off the register as well. I mean on the WIC thing it all seem simple enough when you are going over it and stuff but then when I have a cheese thing I just don't think to look in the book to verify pepper jack cheese although I am sure it would have stated that it is not a covered cheese. I am sure I will have it burned in my memory now though. I also seem to sometimes mess up the buttons when I'm ringing the WIC through I swear I might have done that today!!!! UGGG UGGG UGGGG!