A key only you hold. A file we cannot read.

Install Sunward, sign in with your email and password (and your authenticator code if you use two-factor). The app then asks for your vault passphrase, or your twelve words, once. It downloads the encrypted vault, unlocks it on the new phone with the key it just recovered, and fills in any history days that were missed while the app was not open. Every place, holding, debt and pension is there, and so are your birth year and your projection and retirement settings. The unlocked key is then stored in the new phone's keystore, so you are not asked again. Only two things are per-phone: which categories you hide, and whether the fingerprint lock is on.

Same as above: sign in and enter the passphrase once on each device. Both hold the unlocked key and both read the same encrypted vault. Changes made on one appear on the other the next time it opens.

Whoever has the phone faces your screen lock and, if enabled, the fingerprint lock; the vault key sits behind both in hardware. Your vault is still on the server, encrypted, and the vault file is never stored on a phone: the app fetches it each time with a live login session. So on a new phone, sign in, enter the passphrase, then go to Profile → Sign out on all devices. That revokes every session, including the lost phone's; even if someone gets past its locks, the app there can no longer fetch anything to decrypt. Change your login password as well. There is nothing on the old phone that helps an attacker read the server's copy.

Tap "Forgot password" on the sign-in screen; a reset link arrives by email and opens the app. This is the ordinary account password, which the server knows in hashed form, so resetting it is routine. It is a different thing from the vault passphrase, and resetting it has no effect on your vault.

On a phone that still holds the unlocked key, nothing changes day to day; go to Profile and set a new passphrase while you can. On a new phone, enter your twelve-word recovery phrase instead of the passphrase; it unlocks the vault the same way, and you then choose a new passphrase. The words are the backup for the passphrase, which is why the app asks you to write them down at setup and lets you check them in Profile at any time.

Everything the app kept on the phone goes with it: the session, the cached key, the hidden-category and lock preferences. Nothing is left behind, and the app does not let Android back its private data up to Google Drive. The server is unchanged; your vault waits there, encrypted, until you reinstall or delete it. Reinstalling is exactly the new-phone scenario.

Profile → Export gives you everything as one file, in plain form or encrypted with a password you choose using standard AES-256; the encrypted file carries instructions to open it with OpenSSL on any computer, decades from now, with no Sunward involved. Profile → Delete all data wipes the vault and history and leaves an empty account. Profile → Delete my account removes the vault, the history and your email address. Both are immediate and permanent. Without the app, the same is available by email; see the deletion section of the privacy policy.

The attacker, or the authority, receives what the server holds: email addresses, hashed passwords, and one encrypted file plus two locked key copies per person. The locked keys need your passphrase or your twelve words to open, and neither is on the server. We would tell you about a breach, and you would change your login password; your vault would not need to change, because nothing that opens it was exposed.