Because the bottom of the feet of the character are too close to the edge of the picture, the stands wouldn’t fit into the pciture entirely, that’s why they are outside of the program. 🙂
Please choose the None background (first choice with the crossed circle) for a transparent PNG export, and add the stand and a new background of your choice in a photo editing software of your choice. 😀
You can see some of the results from last years competition here.