How to configure monitoring password ?

Hi,

I'm trying to get the runtime statistics of a Mendix server using a JSON request as described in https://world.mendix.com/display/refguide4/Monitoring :

The JSON request should be accompanied by a base64 encoded monitoring password (the password should also be specified in the application configuration) in the request header"X-M2EE-Authentication". The content type of the request should be"application/json".

My question : where/how to specify this monitoring password in the application configuration ?

I tried the BASE64 encoded MxAdmin password but I get the following response :

{"message":"Authentication failed.","result":-4}

Thanks in advance for your help !

Philippe