I'm using the BYOB 3.1.1 version of Scratch on Macs (OS 10.6.8) in my classroom.
I want to make the default sprite one of my own design (a pretty simple arrow), and tried exporting it to the Costumes folder with the name default.sprite.ysp as per advice from a discussion thread from the Internet (relating to Scratch 1.4). This has not worked. Any advice?