A question, a mistake in a question bank or a problem with the app? Email support@mathtify.com with the app's name, the exam and, for a question, its number or text. We reply in Vietnamese or English.
No. There is no sign-in; your progress stays on your phone.
Only to download a question bank and to buy. Studying and mock exams work offline.
On a new phone or after reinstalling, tap "Restore purchases" in the app, signed in to the same Apple ID or Google account you bought with.
Apple and Google handle payments, so refunds go through them: reportaproblem.apple.com for the App Store, Google Play refunds for Google Play.
Progress is stored only on your phone and does not move to a new one. Purchases do: restore them as above.