Question about backups on iTunes

[dmbpettit]

If I do a backup to iTunes from an iPhone 6 running iOS 9 Beta 2 and then I want to go back to 8.4, can I use the backup that I did when it was iOS 9 to get my settings and apps back?

 

[DeApp1e]

If you want to go back to 8.4, you need to restore the backup you made before upgrading to iOS 9.

Edit: Remember to disable the 'Find iPhone' setting if you're downgrading.