cannot override parameters for other algorithms

[iheo]

When using the Prophet, I wanted to feed a parameter n_chagepoints=25.
Following the page https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/forecast.html,
I tried

forecast.create_predictor(
    ...
    TrainingParameters={"n_changepoints": "25"}
    ...
)

also tried {"n.changepoints": "25"}.
none of them worked.

Error message is:

InvalidInputException: An error occurred (InvalidInputException) when calling the CreatePredictor operation: Invalid Training parameter: n_changepoints specified for algorithmArn: arn:aws:forecast:::algorithm/Prophet 

Is the overriding parameters a supported feature?