I'm not able to use existing test suite created by earlier version of Selenium IDE, also I didn't find any options for using user-extensions.js
One would expect the newer version to have more features and allow some level of compatibility for existing scripts. The real users of Selenium IDE doesn't just record and playback, we create our own custom javascript methods making it more dynamic. I'm not sure if this new version of Selenium IDE is for existing user..or just to get new users to start using this add on. It's a sad day :((