Playback vs Preview options not working

As I am creating an animation sometimes I wanted to just preview the frame and sometimes the movie. Regardless of what I click, I get a movie preview and not just a frame. Any ideas? I’m using Macbook Air, Mavericks and TBS 8.1

You can render/preview a single frame using Effect Preview.

Otherwise use Export Movie and select Current Scene / Camera View and choose the frame under Export Range.