I do not know which Studio one you have , prime, artist or pro but in the pro version 4.62 and 5.01, it is in the bottom right hand corner of the editor window. There are 2 small grey bars you can hover over with your mouse and a "Data Zoom" dialog will pop up. Then just click and drag upward. Note; this is only a vertical zoom for the piano roll or audio waveforms and the 2 bars turn orange indicating you have zoomed in on audio waveforms, not increased their gain or anything else