How to update a field inside an array object in Elastic Search?

Question

Below is a snippet from ES response body. What I want is to update the field inside labels array like for ex "Y" to "Y". I tried "labels.Y":"Y" but it created a field with key "labels.Y" and value "Y". But not traversed to the field inside the labels[0].

---> "labels": [
                {
                    "X": "x",
                    "Y": "y",
                    "Z": "z",
                    "W": "w",
                    "V": "v",
                    "A": "a"
                }
            ],