You can change a height of track as you like. This document describes how to change a height of track.
You can change the height of track according to a drag-and-drop operation when the cursor is changed by moving to the bottom in track frame.
Note
The height of track is determined manually by default. If you want to change the height of track automatically, please select “Auto” of [Track Height] in the track settings. Also please note that some tracks cannot change the height of track automatically.