Terminal still shows older version of rails even after updating

I am a beginner in web development and following the book, Ruby on Rails tutorial by Michael Hartl. I updated my rails using command gem install rails -v 3.2.3 and it seemed to work. But when I checked the rails version using command rails -v, it still shows some different version: Rails 4.2.5.2. I restarted my terminal but no luck. Could you please help me.

Thanks in advance