How to update existing data in firebase?

Question

JavaScript

this is how the data is sent

fetch('https://myproject-c12345-default-rtdb.firebaseio.com/lists.json', {
        method: 'POST',
        headers: {
          'Content-type': 'application/json'
        },
        body: JSON.stringify({title: 'привет'})
      });

in firebase it looks like this.


That is, already in firebase a unique key is created by which data is written.
What needs to be specified in the request url or maybe it is somehow done differently in order to update the data using this key. That is, from the example, instead of the text "hello", set a new value, for example, "how are you"?