How to config max retry count in external worker client

hi all
I’m new to flowable and in my case i have to use external task worker. i have a config in my client for max retry count that i want my task be retried this number of times in case of technical exception. when i fetch and lock an external task for first time as below i receive default retry count 3. how can i determine if it’s the first time task is fetched ? in Camunda first fetch time will return null count so i can understand it’s the first time and set my own max retry count. and then decrement it each time until it reach 0.
my request is as below:

{
"topic" : "test",
"lockDuration" : "PT10M",
"numberOfTasks" :  1,
"workerId" : "workerId",
"numberOfRetries" :  10
}

and i receive this response from flowable engine:

[
    {
        "id": "a9d13c92-4ac4-11ec-9595-9c5a4497ad45",
        "url": "http://localhost:8087/flowable-rest/external-job-api/jobs/a9d13c92-4ac4-11ec-9595-9c5a4497ad45",
        "correlationId": "a9d13c91-4ac4-11ec-9595-9c5a4497ad45",
        "processInstanceId": "a9cd6bf9-4ac4-11ec-9595-9c5a4497ad45",
        "processDefinitionId": "simpleTest:1:9c55a5c1-477f-11ec-9595-9c5a4497ad45",
        "executionId": "a9cfb5ed-4ac4-11ec-9595-9c5a4497ad45",
        "scopeId": null,
        "subScopeId": null,
        "scopeDefinitionId": null,
        "scopeType": null,
        "elementId": "sid-E220EACF-6D87-42EC-A1F2-B641EB2B9D88",
        "elementName": "test",
        **"retries": 3,**
        "exceptionMessage": null,
        "dueDate": null,
        "createTime": "2021-11-21T12:15:06.475Z",
        "tenantId": "",
        "lockOwner": "workerId",
        "lockExpirationTime": "2021-11-21T12:25:28.666Z",
        "variables": [
            {
                "name": "myVar",
                "type": "string",
                "value": "This is a variable"
            }
        ]
    }
]

i got same problem, so anyone here can tell us how can we fix it