Change playback speed?

So on the top toolbar I can change my playback speed of the song. But, it does not stay like that. I can adjust the playback speed, but when I click play, it plays normally (without the change.) Any tips?

Effect > Change Speed and Effect > Change Rhythm.

Select the whole song by clicking just right of the up arrow.

Effect > Change Speed has the same effect as the speed control on a turntable. Speed, Pitch, Rhythm, Everything goes up and down.

Effect > Change Rhythm tries to change the duration without changing the pitch and sound. That may be what you actually want, but please know the software has to rip the sound apart to do that and it’s much more likely to produce damage and distortion.