How I can change the speed of the time lapse?

I'm trying to use imovie to make time lapse videos. When I import my photos from the library and make a project I obtain a video 20 seconds long (for exemple). If I want to watch it in 10 seconds I'm not able to chenge the speed of it.

Why, selecting the clip properties there isn't the cursor to change the speed of the video (with a turtle on the left and a hare on the right) like I saw in some tutorial. I'm not able to play fastly my time lapse videos.

In the properties of the clip I find only these items: "Duration" and "Video effect".

Thanks for the answer.

Ciao.