Can you please try to close the app completely, make sure you're still logged out of all other browsers etc., and then try to log in again?
To close the app completely, from your homescreen double click the home button until it brings up the activity bar- then press and hold the Chess.com Icon until a red (-) symbol appears, then click the symbol :)
I am trying to play on my iPad, but it seems impossible. The system turns me off saying:"another login detected" which seems impossible, I logged out everywhere