Problem with store status as showcase with price or showcase no price

i installed and un installed store open plug-in below and a problem with configuration-my store-
store status function. even if i set up the store status as showcase with price or no price, add to cart button is appear on the main page in featured products, specials and new product listing but no add to cart button in the prodect description page.
it seems that the module have changed some original file.
do you know which file is changed by the plug-in below?

http://www.zen-cart.com/downloads.php?do=file&id=943

The module says it makes no changes to core files. Did you remove ALL the files relating to this module? (there are three of them)

Did you run the UNINSTALL.SQL patch?

Did you BACKUP your system before installing this mod (The README advises you to do this)?

i cound not find what is the ploblem so i need to remvod the ADD TO CART button of futhered product list of main page.
Which file should i edit to remove it? and what code need to be removed..?