Derive question: Need help restricting domains on Derive software...

I am working on a math project in which I hope to do a presentation on. For it, I have come a very unique function. However, part of the function is supposed to be negative and part is supposed to be positive and alternates forever (like a sine or cosine function). However, the one that I'm able to graph can be either entirely negative or entirely positive.

To resolve this issue, I need to be able to restrict the domain of this function. I know how to do this on a Ti-84, but not on Derive (which is partly how I'll be presenting this). I know there is an "Author Tab" and from there there is a "Variable Domain" button. With that, I can't "restrict my domain" of the function. At least I would, if Derive wasn't such a SOB to figure out. When I highlight my equation and try to restrict my domain, it spits out the domain numbers in a completely new expression and doesn't even apply it to the one I have.

Is it me, or does Derive have a bug, or is it just flat out not a user-friendly software? Could someone tell me where I'm going wrong, and maybe how to fix it (in slow, simple steps?). Thank you in advance.

By the way, I prefer derive above most other programs because of it's "slider bar" feature for graphs. That DEFINITELY will come in hand for my presentation.