Hey, so I'm not amazing with sound design. I was given Bfxr by my instructor during my diploma of screen back in 2007 and have been using it ever since for quickly making placeholder sounds. Recently I started working on a game that requires classic 8-bit style sound effects and picked it up again. However, I found for whatever reason, depending on the operating system I'm running at the time, Bfxr reads the sound files slightly differently and produces different sounds to the ones made elsewhere. Because I switch from Linux and Windows constantly throughout the day, I needed something more consistent. So I started using Jsfxr Pro. It's mostly the same, I'm able to cloud-save my work and organize it neatly. But if I want to mix say for example a white-noise with a saw, I have to make them individually and open them up in audacity. Which is not a big deal or a deal-breaker or anything. It's just something Bfxr did really easily. But it is very, very, very old software. I'm honestly amazed at how well it holds up to this day.
Now, my only issue with both Jsfxr and Bfxr is that I'm not very good. I feel like a chimp holding a paintbrush. I get what the tools do but I'm not good at using them. :D
It would be great if there was a video series (probably is) online that taught you how to make a series of common but complicated sounds by teaching you what each value does.