USER: {
  _id: objectId(as425as4526dc)
  username: 'admin',
  password: 'a61a8726ahf604s',
  fname: 'first',
  lname: 'last',
  date: '2018-9-9',
  orders: [
    {
       _id: objectID(012eoisadn3)
       status: 0,
       name: 'name'
       description: 'hello'
    }
  ]
 }

const username = req.body.username;
  const orderID = req.body.id;
  const newStatus = req.body.status;

  User.update(
    {
      username: username,
      'orders._id': orderID
    },
    {
      $set:{
        'orders.$.status': newStatus
      }
    },
    function(err,docs){
     ...
     //Do Stuff Here
     ...
    }
  );