JBL GO+

First, remove the speaker from your source device's Bluetooth settings.
Power on the speaker, then press and hold the Volume + button and Bluetooth button together for 3-5 seconds until the speaker turns off.
Once turned off, the speaker has been reset to the factory default settings.

With some phones, such as iPhones and some Android models, volume is synchronized while Bluetooth is used, and levels below volume setting 6 (tested with iPhone 6 and iPhone 5s) and volume setting 5 on most Android devices will cause the GO to enter standby after some minutes. If you want to play softer while still using your iPhone as a source, please change to cabled connection from the headphone output to the AUX input of GO. This will make it possible for you to set the GO's volume at its minimum step, and then control total level on the telephone. Of course, if source level from the telephone is set extremely low, the GO will go into standby again, because GO needs a certain level to keep playing. Alternatively, use a phone which does not synchronize volume as source. Many Android phones do not synchronize volume, so by using such a phone, you can adjust GO to its lowest level, adjusting total level independently, even via Bluetooth. This will usually result in music volume at the desired level.