Say which game you were playing and what happened,, and include a screenshot if you can.
Pick the game, then tap the ⓘ button at the top of the screen. Every game has a short how-to-play sheet.
No. Every score is saved as you enter it. Open the app and tap Resume on the Home screen.
Only on your phone. There's no account and no cloud copy, so deleting the app deletes your history. See the privacy policy.
On the old phone, open Past Match Results and tap Export backup, then send the file to yourself. On the new phone, tap Restore and pick the file. You can merge it with what's already there or replace everything.
No. It works out who owes whom and remembers what's been paid. Settling up happens however your group normally does it.
Up to six, depending on the game. High Low is played as two teams of two.