Override Modal Content?

How do I override the content in a Modal? I basically want to change the login and register modals.

Or is it possible to disable them? Change the event that triggers them?

I have tried directly overriding the LogInModal.content function in my extension but the changes are not reflected.

LogInModal.content = function() {
console.log("Hello");
};

After a fresh install of Flarum I was able to get this working:

LogInModal.prototype.content = function () {
return [...,...];
}

I'm not sure why it did not work to begin with. ?