If you post in "Stock images & Resources" you are basically allowing your images to be used in other artists work as stock. (example: background image or texture) It all has to do with the category you submit to. You can always go to the "edit" preference in your submissions to change the category. To be honest: people will probably end up using your image to create manipulations unless you change the category. Of course, when we create artwork- or most of us rather, we do link and credit the stock provider. I think submitting stock is a great way to be recognized though- just personal opinion. But if you don't want your image(s) being used for others to create artwork I would strongly recommend changing your submission category. Welcome to DA. If you have any other questions I'm happy to be of service.