How do I go back to IOS 8 on my iPod 5th generation? There is a lightning/USB cable issue with GM Bose units and I want to go back to IOS 8 pending Apple’s correcting the problem with IOS 9.

There is a lightning/USB cable issue with GM Bose units regarding IOS 9, and I want to go back to IOS 8 pending Apple’s correcting the problem with IOS 9. This is a pretty significant issue with Bose and Harman Kardon sound systems in the GM family of vehicles. When an Apple device is connected with the USB/Lightning cable, crackling and popping results… This is not present on an earlier Classic iPod, but present on ALL my current devices with IOD 9 installed.

Thank you.