In order to make item class changes or update attributes to your items please follow the steps as mentioned below:

1. Within the seller portal go to Products > Product Mgmt > Bulk
2. Under ‘Step 2’ click the “Show Item Classes Where I Sell Items” radial button
3. To see all items you can select the respective item class and then click Download
4. Select “Generic Template (with Items)”
5. Once downloaded, you can review all of the items
6. Attribute the items and change the item class id and path in the generic template
7. Once completed, upload the template
8. Review the error report if applicable
9. Any information that you upload for a particular item will overwrite the previous