Email fauxapps@gmail.com. Say which handheld and firmware you use.
RomRoster tries each firmware's documented default sign-in first. If you changed the password, or your firmware shows a generated one in its settings, type that one. The Steam Deck uses the password you set for the deck user in desktop mode.
Tap the hide icon on its row, or open it and choose Not a game: hide it from the list. Hidden items stay hidden through rescans. Bring one back under More > Hidden items.
Open the game and choose Rename, or Search for a cover by another name.
Open More > RomRoster Pro and tap Restore purchase while online, signed in to the store account that bought it.
No. It only reads.