At ur htdocs files, image folder... U must edit the item id at ur sql databse. If u use xampp go to phpmyadmin, acess ur database and in the id of the item u putted in the shop, put the number that correspond to the image u want.
Example: if the cooper shield id in images folder are 55, u must put this number 55 in the phpmyadmin, u must change the number id of the shop offer and put the number of the image folder, in case this number is 55.
Sorry shit english, im from brazil.