look for download link for "old" ios 8.3
How can i find a download link for 8.3 on apples website?
i update to 8.4 but i will back to 8.3
iPhone 6, iOS 8.4, iOs 8.3
Sorry, but it's not possible to revert to a prior iOS.
if you needed to restore a device at this point, it would restore to iOS 8.4.