Bose App
Appearance
As of 2025 The current app for Bose Portable PA is the Bose App.
This applies to all L1 Pro and the S1 Pro+
Get it on the Google Play Store or the Apple App Store.

Hint
Place your finger in the middle and then drag your finger up and down over the control (like a vertical slider). That works well and it is easy and intuitive.
Tap in the middle to toggle through Volume, Treble, Bass, Reverb - OR Tap on the words Volume, Treble, Bass, Reverb Don't try to rotate or drag around the control.