• Restoring from a recent iCloud backup is the simplest and fastest way to set up your new iPhone. Tap Restore from iCloud Backup during the initial setup process, sign in with your Apple ID, and then select the most recent backup of your old iPhone.
• To do so, go to your previous phone's Settings app and look for iCloud Backup (click the symbol), then pick Back Up Now. Once everything is back to normal, you'll need to sign back into any accounts you added to your phone and double-check that you're still signed in to all of your apps.
• or Make sure you have both phones, preferably connected in and charged to avoid running out of battery, a Wi-Fi connection, and enough time for the procedure to complete — it could take more than an hour.

Read More: How to use iBooks and manage PDF documents on your new Apple iPhone X