New Task Reportable

When i create a new ad-hoc task, i want it to automatically be set to "reportable" and "actual effort updated from timesheets". I have tried amending the default value of "reportable" in settings but this option is greyed out.

Is it possible for further automation in this respect: say a user creates an ad-hoc task related to a certain customer and is a particular task type, then this task is reportable?