Email notchsupport@gmail.com and you'll hear back within a couple of days. Include your iOS version and what you were doing when the problem happened — screenshots help a lot.
Where is my data? On your iPhone, and nowhere else. Notch has no accounts and no cloud. Settings → Data shows automatic daily backups you can restore anytime.
How do I move to a new phone? Settings → Export backup file on the old phone, send the file to yourself (AirDrop works great), then Settings → Import backup file on the new one.
How do I import my assignments? School → Bulk → Paste list (copy your Canvas assignments page) or Scan screenshot. Every title, date and time fills in automatically.
Something looks wrong after an update. Settings → Data → Automatic backups — restore yesterday's snapshot. Then email us so we can fix the bug.
The short version: we collect nothing. Read the full privacy policy.