Can a previous iOS be installed on iPod Touch?

I have an iPod Touch, Gen 5, that has iOS 8.3 running. I updated the OS last month and since then I am unable to use my Bose MiniLink Bluetooth Speaker using Bluetooth. Prior to the update the Bose system was easily detected so, after finding that resetting/wiping my iPod clean did NOT fix the problem, I am left to believe the problem is with iOS 8.3. The iPod does detect my MacBook Pro laptop, just not the Bose speaker so maybe it's a "driver" problem but cannot find anything about this on either the Bose web site, nor Apple support board/discussions.

Sooooo..... do you know if a prior iOS can be installed "over" the current one and, if so, can you either direct me to a site that explains how to do this, or provide instructions on how to do so?

Thank you, in advance, for your assistance.