What Changes When You Switch Phones

Moving to a new phone is three different operations depending on how you do it, and each one carries a different amount of app state. A direct device-to-device transfer moves the most. A restore from a cloud backup moves less. Reinstalling from the app store and signing in moves only what the operator holds on its servers. Nobody tells you which one you performed, and the differences only surface later.

For a companion app, the visible symptom is usually the same regardless: things you had set are back at their defaults, and possibly the history is thinner than it was.

The three migration paths

They are worth distinguishing because the outcomes differ.

Direct transfer copies app containers between devices over a cable or local connection. It generally moves the most local state, including data some apps exclude from cloud backup. It requires both devices present and takes the longest.

Cloud backup restore rebuilds the new device from your platform backup. What arrives is limited to what was backed up, which is a per-app developer choice discussed in what ends up in your phone backup. Anything an app marked as excluded is simply absent, with no notification.

Fresh install and sign in moves nothing local. Everything you see afterwards was fetched from the operator’s servers. If the app is server-backed you may notice nothing at all; if it kept meaningful state locally, that state is gone.

Cross-platform moves — one mobile OS to the other — are always effectively the third path, because the migration tools that exist between platforms handle photos, contacts, and messages, not arbitrary third-party app containers. Expect to be signing in fresh regardless of what the transfer wizard implies.

What reliably survives, and what reliably does not

The pattern is consistent once you know where the line falls.

Survives, because it is server-side: your account, your subscription entitlement, and whatever conversation history the operator stores. Also any persona configuration held in your account rather than on the device.

Survives if backed up, otherwise not: local caches, local drafts, in-app preferences that were never synced, and local history in apps that store it on the device.

Almost never survives: permission grants, notification settings, and anything else the operating system holds per install. A new install starts with nothing granted, which means you will see the prompts again. That is a feature — it is a free opportunity to grant less than you did last time, per what a permission prompt actually grants.

Survives inconveniently: app-store subscriptions, which are tied to your store account rather than the device and continue billing through a migration, a gap, and a reinstall. This is how people end up paying for an app they no longer have installed. See who you actually bought the subscription from.

Do these before you wipe the old phone

The old device is the only place some things exist, and it stops being available the moment you erase it.

Confirm you can sign in on the new device before erasing the old one. This is the whole game. If the account uses a platform identity, the sign-in should be seamless; if it uses an email and password you set up months ago and never wrote down, find out now. See what sign in with Google or Apple links together.

Export anything you want to keep, while the app on the old phone still works and while you still have the account. Export flows are typically account-scoped rather than device-scoped, so this is less urgent than it sounds — but it is easier to do on a working install than to arrange later.

Note the subscription channel so you know where to manage it afterwards.

Then erase the old device properly, using the platform’s own erase-all-content function rather than deleting apps individually. A factory erase on a modern phone destroys the encryption keys, which makes the remaining data unreadable — that is a much stronger guarantee than any amount of manual tidying, and it is the correct final step for a phone you are selling, trading in, or passing on.

If the old phone stays in the household as a spare or gets handed to someone else, the considerations in what a shared device exposes apply from that moment.

Two devices at once

If you keep both phones running for a while, note that some apps allow only one active session per account and will sign the other device out, sometimes without a clear notice. Others allow both and sync between them. Neither behaviour is documented prominently.

Where two devices are both signed in, both hold local copies, which doubles the number of places to clean up later. If you are keeping a spare phone with an active session, that is a decision worth making deliberately rather than by inertia.

What this does not tell you

A migration tells you nothing about the operator’s copy of your data, which is unaffected by anything happening on your devices. It also cannot tell you in advance which of the categories above a specific app falls into — you find out on arrival at the new phone, when either everything is there or it is not.

The one thing you can reason about beforehand is what the app does with no network connection, which is a decent proxy for how much it keeps locally; that test is described in what airplane mode tells you about an app. An app that is entirely inert offline is holding almost nothing on the device, and will migrate cleanly by any path.