Hi! Please don't edit or crop the level cards you upload. It may result in problems on scanning the level.
Welcome in the forum @Conradiculous. Yep... At least you can edit the thumbnail of the media (Usually for a focused view on the level rendering in the galery), but the image attached to the media needs to be the original one (exported or a good quality screenshot). For more informations it is stronghly recommanded to read the documents of this thread in the forum. Thanks in advance.