I've seen this same situation pop up enough times that I've been getting a bit annoyed, to be honest, to the point where I ended up posting a comment on andritolion's 3DS OS. Basically, someone copies someone's program and reuploads it as their own, or just modifies it slightly, and gets the original creator upset and trying to force the reuploader to add attribution, take down their program, etc. A similar situation is trying to license SmileBASIC programs with something like Creative Commons (which is not even close to correct, I'll elaborate on this). I'd like to explain a few things in this forum thread so people can properly understand what it means to release a program on SBS.
First of all, I want to point out some important things so that people can understand licensing a little. So what is a license anyways? Basically, a license is a way to copyright a work (photos, data, source code, etc) while allowing other people to modify under certain conditions. However, there are different licenses for different things. Creative Commons licenses are meant for photos and other kinds of data, and do not cover things like patent rights, don't contain important parts required for distribution of source code, etc (read up at https://creativecommons.org/faq/#can-i-apply-a-creative-commons-license-to-software). What you should use is a license meant for source code. Most people would want something like the MIT License (https://choosealicense.com/licenses/mit/), which forces people modifying source code to keep copyright notices in code and to redistribute the license with their source code.
So this must be the solution to protect your SmileBASIC programs, right? Well, no. As stated in the SmileBASIC manual (http://smilebasic.com/en/e-manual/manual13/),
Please also note that programs and resources (images and sounds) included in published projects are deemed to have been provided by their creators with permission for secondary use by third parties. Please be careful to avoid problems such as infringement of copyright. If a published project is the subject of a takedown notice, SmileBoom Co., Ltd. may delete the relevant project without prior notice.As this should make obvious, the moment you release your project, you're giving anyone permission to use your code for whatever they want. I doubt that anyone reading this would be able to contact a lawyer and have them submit a DMCA takedown for something you don't (and can't) have registered copyright for, so you're officially screwed. If they can read your code, they can do whatever they want with the code. So you can't do anything. Even obfuscation won't protect your software, as it isn't very difficult for someone with the intelligence to do so to completely reverse your obfuscation to something that makes sense. In short, you can't do anything about people stealing your code. You can try as much as you want, but you sign away your ability to protect your software the moment you tapped "Publish my 'secondary-use-free' Project", so tough luck. The best you can do is try to ask an administrator to take down the program (check http://smilebasicsource.com/staff to find someone with Page Moderator or Admin and send them a site PM from http://smilebasicsource.com/messagebox), but even then, you might not have any luck. Not everyone is nice enough on the internet to attribute those they copied from, and you need to learn to accept that.