The Aeros does not currently change tempos in the middle of a song, this is because it does not support changing tempos while recording, or playing back. A song must record in one tempo, and playback in that tempo.
We do hope to allow this at some point, but it is not a high priority right now, and it is not the intended use of the pedal port, which most likely would be to control volume (to use instead of the volume wheel), but we have not explored it very much yet.
If you’d like to change the tempo quickly, and there is no MIDI sync activated, the Aeros can quickly be set to any tempo using the tap tempo button (bottom left).