To my knowledge Protune is not available on the Hero3+ Silver. This link describes some of the models where it is available: https://gopro.com/support/articles/how-to-use-protune

Unfortunately us with 3+ Silver are out of luck. Even with the new 3.02 firmware update. I think you would need the 3+ Black model or the higher end Hero4 models.

 

the top models get the better of the Firmware upgrades back then, and now the Hero 4 Silver and higher are now up to par for protunes