How to change the number of products per page in PrestaShop
On the product list pages in PrestaShop there are ten products displayed by default. You can change that default number from the back office of your store.
After you log in to the admin panel of your PrestaShop click on the Preferences tab and then on the Products sub-tab. On the page that opens find the option Products per page, change the number to whatever you want and click on the Save button.