Changing Post Per Page Does Not Update Products on Shop Page

I have tried to update the amount of products displayed on the shop page multiple ways. I tried updating the posts per page option inside of wordpress and also by adding the code that WooThemes put out to the functions.php file:

// Display 24 products per page. Goes in functions.php
add_filter( ‘loop_shop_per_page’, create_function( ‘$cols’, ‘return 24;’ ), 20 );

Neither of which change the amount of products from 12. I am assuming there is code in the files somewhere that is overriding these, can you please point me to where I can update this number?