On the timeline, click on an audio track or select multiple audio tracks [Ctrl+🖱], and then you can find the Speed option in the toolbar above.

Here, you can drag the slider to change the audio speed freely, from 0.2x to 8x. Besides, you can enter the speed in the top box, or enter the aimed duration of this audio in the bottom box.

It should be noted that the length of an audio track cannot be shorter than 0.1s, nor longer than the entire video project.