You can locate the product that needs to be modified by searching for it using the Locate a Product feature. Once you have located the product, click on Details to view and modify product properties such as name, prices, descriptions, images, etc. The form that is loaded is very similar to the Add New Product form. Refer to that section of this WIKI for more information on each form field.
There are a few differences between the Add and Modify product pages:
Category Assignments
With regard to the categories that the product has been assigned to, the Modify Product page lists all the categories to which the product has been assigned. You can easily add or remove categories to the list by clicking on the Edit Category Assignment button. Click on the check box next to the categories to which you would like to assign this product, then scroll to the bottom and click on the Update button.
Additional Product Images
With regard to product images, you can now take advantage of the Additional Product Views feature. This feature is not available until you save a new product, and therefore it is not available on the Add New Product page.
Test License Generator
If you are modifying a Downloadable Product, the Test License Generator feature will now be available to you. This feature is not available when you are adding the product to the store as ProductCart first needs to save product information to the database before being able to test the license generator associated with the product. You can now also verify the download
URL.