Moving to a new iPhone or iPad does not affect the photos already on your Ultimate Backup — they stay exactly where they are. What changes is what the app on the new phone knows, and that is worth understanding before the first backup runs.
Before you switch
While you still have the old iPhone, run one more backup and let it finish. How do I know if all my files were backed up? shows what a finished backup looks like. If you want your contacts on the drive as well, make sure Contacts is switched on before you start — only what is backed up can be restored later.
Two things to expect at this stage. An old iPhone with no cell service still backs up perfectly well over Wi-Fi. And photos kept only in iCloud have to download to the phone before they can be copied, which also needs Wi-Fi and can take a while.
When it has finished, eject the drive before unplugging it.
Setting up the app on the new iPhone
An iPhone set up from an iCloud backup or a Quick Start brings your settings across to the new iPhone. This means you can likely skip some of the initial setup steps.
Install the app, then sign in with the account you used on your old phone. If you do not remember its password, you can reset your password. If you no longer have access to that email address, create a new account instead — your backups are not tied to your account, so nothing already on the drive is lost. See Do I need my account to reach my files?
Choose your product when asked.
If you use a MAX drive, or connect any drive over USB-C, you also have to tap Grant Access to Drive and choose the drive in the Drive Picker. Access is granted for one phone and one drive together, so a second drive on the same phone has to be granted as well. This is the step that catches people out, because on a Lightning iPhone a 4-in-1 simply appeared. There are screenshots in App Setup for iPhone or iPad, and Got a new phone? covers which drives fit which port.
When the first backup starts, the app asks for access to your photos and, if you want them, your contacts. Allow full access to the photo library rather than selecting individual photos, or the backup will only ever see the few you picked.
What the first backup does
The drive keeps each iPhone's backups in a folder named after the phone — the name under Settings › General › About › Name. An iPhone restored from an iCloud backup normally keeps the old phone's name, which simply means its photos carry on in the same folder as before. What decides how much that first backup copies, though, is not the name but whether the app's record of what it has already backed up came across with the phone. The name only decides which folder the photos go into.
If you set the new iPhone up from the old one — with Quick Start or from an iCloud backup — the app's record of what it has already backed up comes across with everything else.
If you installed the app fresh, it has no record at all and the first backup copies everything again. Where it puts those files depends on the name: a new iPhone with the same name writes into the old phone's folder, where a file of the same name is written over rather than doubled; a new iPhone with a different name gets a folder of its own, which means a second full copy of your library, so check the drive has room for it. Most iPhones set up as new are given a different name, so that second folder is the more common outcome.
A first backup that has to copy everything again takes as long as your original one did. Start Backup or Resume Backup: what's the difference? explains what the button is telling you, and Does a second drive start where the first one stopped? covers the same ground for a new drive.
If the backup ends early
A brand-new iPhone is usually still pulling your library down from iCloud, and the app can only copy what is actually on the phone — so the first backups often stop short and report that the backup is incomplete. Let Photos finish downloading, keep the phone on Wi-Fi and on charge, and then run the backup again the next day. Troubleshooting an Incomplete Backup has more.
Getting your files onto the new iPhone or iPad
Connect your drive to your new iPhone or iPad. Restore Files only appears while it's connected. Open Settings, then Restore Files. The list holds every device that has backed up to this drive. Choose the whole device, or open it and pick what you want.
Restored photos and videos go into your Photos library with their original dates, rather than into an album of their own, and contacts are added to Contacts. The app attempts to skip anything that’s already on the new iPhone. For other files, like documents and music, the app prompts you to save them to the Files app. Copy Files from Ultimate Backup to iPhone or iPad has the full steps.
KeepSafe
KeepSafe follows your account, so signing in with the same email address is all it usually takes. If your subscription does not appear, tap KeepSafe, then Options, then Restore Past Purchases. Billing stays with the store you subscribed through (Apple, or Google Play if you subscribed on an Android phone). Sign in with the same account; don't subscribe again. KeepSafe Overview covers the rest.
If you need any additional assistance, please contact Ultimate Backup support.