First: Go to your costume. Then In the top corner go to the thing that says file press that and it should give you multiple options press save to computer if you have a phone its most likely to say PHONE instead of COMPUTER.... Second: press that! It should then down load to your device and then any time you need it, go to the same thing that says file and instead of down loading a costume you can upload it instead! WARNING: Do NOT upload a sprite if you have already drawn of saved other costumes of even coded any thing! It WILL wipe every thing out!!!
Wait like ten seconds between each one :)