The iCloud or iTunes backup of your old iPhone makes it easy to move into your new digital home at that fancy address called iPhone 6s or iPhone 6s Plus. But you want to furnish your new digs properly — and not leave anything behind that you’ll miss. Here’s one tip that helps ensure your data transfer is a breeze. Upgrade to the newest iOS on your old phone before you move.
The iOS compatibility will help the backup and then the transfer. So if the iPhone you’re moving from will support the latest iOS, do it. That’ll make backing up to iTunes or iCloud and subsequent transfer to your iPhone 6s more seamless. On your current/old phone go to Settings > General > Software Update. If there’s a new version for you, install it.