Trying changing this:
$query_new_user_update->bindValue(1,':user_balance', $ubalance, PDO::PARAM_STR);
$query_new_user_update->bindValue(2,':user', $user, PDO::PARAM_STR);
$query_new_user_update->execute();
to
$params = array(':user_balance' => $ubalance, ':user' => $user);
$query_new_user_update->execute($params);