Update a value inside a nested document

Working with Data Drivers
,
1

I’ve been having trouble trying to update values inside a nested array. My data structure is as follows.

{
    "_id" : ObjectId("616e840755595c5d353a1eb3"),
    "User" : "Aaron *******",
    "Email Address" : "************@outlook.com",
    "Password" : "*********************************************************",
    "gender" : "male",
    "phone" : "*********",
    "dob" : "1972-08-09",
    "MBTI" : "{\"I\":45,\"N\":20,\"T\":25,\"P\":65}",
    "jobs" : {
        "a1" : 0,
        "a3" : 0,
        "a18" : 0,
        "a19" : 0,
        "a25" : 0,
        "a35" : 0,
        "a36" : 0,
        "a48" : 0,
        "a52" : 0
    },
    "HC" : "[\"C\",\"R\",\"I\"]"
}

I have been using the following code to attempt to update values inside the nested jobs array.

$userdata = (new MongoDB\Client)->kalgu->userdata;
$user = $userdata->findOne(array('Email Address'=> $email));
$updateResult = $userdata->updateOne(
                ['_id' => $user['_id']],
                ['set' => [$user['jobs'].$career=>$new]]
            );

This results in the following error - Fatal error: Uncaught Error: Object of class MongoDB\Model\BSONDocument could not be converted to string.
Can someone please tell me what I’m doing wrong?