Please be aware that at this time you’ll need to create your Amazon Handmade items through Vendio in order to manage them through Vendio. If you have created an item through Vendio for Amazon Handmade then you can edit it from your Vendio account by going to Items → My Items. Then put a check mark in the box to the left of the item or items that you want to edit, click the Actions button, and then select Send To → Amazon Handmade. From this page you can make any edits that you need (only the category cannot be edited after the item is created).
When you are done you can click the Save Only button to the right of one item to save the changes without sending them to Amazon. The Save & Sync button to the right will save the changes and also send them to Amazon. If you are editing more than one item at a time then you can use the Save All button at the bottom to save all of them, or the “Save & Publish Amazon Ready Items from this list” to save the changes to all and send them to Amazon.