The values for maxBufferSize and maxReceivedMessageSize are not propagated to the WSDL file that is published by your service. That´s why the wcf test client is unable to retrieve them and takes default values.
You can still change the values with the SvcConfigEditor every time you start the wcf test client. Therefor perform a right click on the config file in the wcf test client and look for bindings. But the changes will be lost, the next time you start the client.
You can also test your service with a self written client and set the values there like shown in the following example.
BasicHttpBinding binding= new BasicHttpBinding();
binding.MaxRecievedMessageSize = yourValue;
EndpointAddress endpointAddress = new EndpointAddress("the address");
ClientForContract client= new ClientForContract (binding,endpointAddress);
client.TheMethod();
client.Close();
Hope this helps!