when I was flying a few days ago, the gain & expo settings were keep resetting to default.
anyone else had this issue?

Hi there. Thank you for reaching out and we're sorry for the trouble. Can you please try to reinstall the DJI Fly app on your mobile device to see if the issue persists? Does the issue occurs after you restart the app or it will automatically reset after you configure the settings? Please keep us posted. Thank you.