The WP e-Commerce plugin (WPEC) comes with three WPEC themes: the Default theme, the iShop theme and the Marketplace theme. You can select the WPEC theme you want by navigating to the Store panel and Settings sub-panel under the Presentation tab under 'Select Theme'.
WPEC themes are not the same as WordPress Themes. You can edit the WordPress theme files with the editor under the Appearance panel but the WPEC themes are edited with the editor under the Plug-ins panel. WordPress themes are located in the / wp-content / themes / folder on the server while the WP e-Commerce themes are initially installed at / wp-content / plugins / wp-e-commerce / themes folder. This folder is fine except for one thing. When you update WPEC using the automated updater it will remove this plug-in directory and replace it with a new directory with the latest Plug-in files. If you have customized any of the WPECe theme files then you will lose all of those changes.
To prevent this from happening you will need to move these WPEC theme files to a safe location. Fortunately this is an easy process and can be done with a few clicks. Navigate to STORE >> SETTINGS >> PRESENTATION. On the right is a box titled THEME CUSTOMIZATION. Click on the MOVE YOUR FILES link and this will move the STORE THEME files to a new location in the uploads folder.
After the WPEC files have been safely moved to the new location at / wp-content / uploads / wpsc / themes, you can make any change to the theme files from this new location and they will be safe from any future updates. After you move these WPEC theme files to this new location you will need to edit them outside the WordPress environment. The new location is not available for editing with the WordPress plug-in editor. You can still edit all the other WPEC files with this editor.
The box now gives you the location of the moved files and brief instructions for creating a new theme for customizing the appearance of the store.