Failure to make route to change doubled nested schema

I am having trouble updating a certain field within a nested schema. The schema layout has a user that a few fields and the classes field calls another schema called class schema. This schema has a class name and a projects schema as well as the total amount of time spent on that class. The project schema has two fields with a name and the time the project took.

I would like to be able to change a class project time spent and here is what I have so far. Any help would be greatly appreciated. I am new to this.

router.route(’/update_classes/:id’).post((req, res) => {
User.findOneAndUpdate({id:req.params.id}, {classes: { projects: { timeSpent?: { timeSpent.body.classes}}, {new :true}, (err, doc) => {
if (err){
console.log(err);
}
else {
console.log("Updated User : ", doc);
}
});
});