You have two ways to edit products you have already set-up or use them as a template for new products:
You can alter your products within the Marketplace and your shop separately, or together in one quick move. If you edit your product within the Product Overview (have a look at the link to the right of the product image – click on 'Show All' in the drop-down menu,) then it will be changed in both your shop and the Marketplace (should you have published it in both forums).
Here's how it happens in a bit more detail: your original product is deleted and directly replaced with the newly saved version (e.g. with a new design or in a different color.) The settings from the original product (such as the commission level) will be automatically transferred to the new one, and it will be placed at the top of your 'product overview' list.
Please note: changes to products in this way will alter it with both your shop AND the Marketplace. Should you wish to edit a product in just your shop OR the Marketplace – select the desired forum using the drop-down box in the top left of the screen (you can choose SHOW ALL to edit in all places; MARKETPLACE to edit just in the Marketplace and the same is true if you select SHOP )
If you want to set-up a similar product to one you have already created, but don't want to delete the original, then click on the 'Use Product As Template' option. A copy of the product will be created – which you can freely edit without changing the original