Can I sell my writing elsewhere?

I work as a "volunteer" for an online magazine. I have not signed any contracts with this magazine, and they haven't paid me anything. The agreement four months ago was that once the magazine made ad revenue, all staff would be paid. They said it'd be three months, but I still haven't seen a dime.

I've written several articles for this magazine. They have a disclaimer inside that says they own all of the content (it's their copyright) but like I said, I never signed any contracts with them and they haven't paid me anything.

Can I sell these articles to another publication (one willing to give me a contract and actually pay me)? Or can I at least rewrite these articles, retitle them, then sell them elsewhere? I'm concerned about getting sued, but from what I understand, there's not much they can do without a contract....