To Enable Boost Volume, please follow all these steps:
1. Open The VoicePing Application and Make sure that you are logged in to your account.

2. Tap the 3 dots icon at the upper right corner of the display.

3. Choose "Settings" option.

4. Go to "PLAYBACK OPTIONS" section then enable the "Boost Volume" with a tick by tapping it.

For a clearer guide, please check out this video: