Creating and updating measurements

I need some elaboration on creating a new measurement and updating it.

Using this URL:

I have created a new test measurement related to single-phase energy meter as shown in fig(test_measurement) but how to update this newly created measurement if use the same URL with a different value it creates a brand new measurement instead of updating the values of previously created measurement as shown in fig test2 also the measurement data is not visible on UI.

The id of the new measurement is generated by the server and returned in the response to the POST operation. For example, in your case id is 1846671.
Try updating using the measurement ID.