I recently upgraded to 3.3 and now I can't use the 'Use as Thumbnail' feature in the Media Gallery to assign pictures to my products. Now, the only two things I can do is 'Insert into Post' or 'Delete'. What happened to the 'Use as Thumbnail' option? It now wants me to upload an image for every item I have. This is terrible because I want to be able to use one image for multiple products I have but it won't let me do this. What can I do?