How to set current user in Azure Blockchain workbench through REST API?

Question

I am new to Azure blockchain workbench. I have created an application. Now I am trying to preform operations through REST API. I can create users using POST /api/v1/users. I get the userID in response. I am also able to verify this using GET /api/v1/users.

But when I use the api GET /api/v1/users/me , I get the following response-

{
    "currentUser": {
        "userID": 4,
        "externalID": "c737863b-17d7-4d66-be78-7b3e1b9d66af",
        "firstName": null,
        "lastName": "",
        "emailAddress": null,
        "userChainMappings": [
            {
                "userChainMappingID": 4,
                "userID": 4,
                "connectionID": 1,
                "chainIdentifier": "0x53ab468b227edef755cd77198da00eeab1d0ed09",
                "chainBalance": null
            }
        ]
    },
    "capabilities": {
        "canUploadApplication": true,
        "canUploadContractCode": true,
        "canModifyRoleAssignments": true,
        "canProvisionUser": true,
        "canUpgradeWorkbench": true
    }
}

I tried using this external ID to set the first name, last name, email. But I am still getting NULL here. How do I set the current user to the one that I have created through API?