Can You Change Pitch in iMovie?

Click on the video. Look above the small display frame at all the icons. Click the audio icon. Then you can change the volume and pitch of your movie audio.

Is there a way to speed up audio without changing the pitch in iMovie?

Drop your clip into a comp. Right-click and choose “Speed/Duration” and change the speed to what you want. Add the Pitch audio effect, and adjust the Semitone Shift property to return to the original pitch.