Meteor: Trying to add custom field to users() but it didn't success

I have been trying to add these custom fiels into user account system of meteor under the profile, but it wasn’t success. I have a modal form, which is pop up to do that and below is my code on the events.

Template.profile.events({
'submit #saveBasicProfile': function(event, template) {
console.log("CLICK");
event.preventDefault();
var fullnameVar = event.target.fullname.value;
var titleVar = event.target.title.value;
var about_youVar = event.target.about_you.value;
Meteor.users.update( {_id:Meteor.user()._id}, 
        { $set: 
            [{ "profile.fullname"  : fullnameVar }, 
             { "profile.title"     : titleVar },
             { "profile.about_you" : about_youVar } ]
        });

//Router.go('/profile');
}   
});

In principle it would look something like this:

Meteor.users.update( {_id:Meteor.userId()},
  { $set: {
    "profile.fullname"  : fullnameVar,
    "profile.title"     : titleVar,
    "profile.about_you" : about_youVar
  }
});

However, I would (a) advise you to avoid using the profile field, and (b) to do this in a Meteor.method, where you can be much more secure about the user Id. Check these Meteor Guide articles:

That last one will apply if you move this functionality into a method.

Thanks @robfallows! Well, I don’t want to use the profile in the useraccount system too, but I have a form sign up with a user’s fullname, is there anyway to add them into different collections from my custom form?