Hello Mushtaq,
I believe you should be able to select the knowledge area on which you want to practice, as long as you pick either the timed or the learning mode. Please see the attached screenshot which may help you through the process.
Domain selection should also be available; see this page for further details:
www.pm-exam-simulator.com/features/three-exam-modes
.
Feel free to contact the technical support at
support@pm-prepcast.com, as they may be able to better help you with any technical issue you might experience with the PMPrepCast Simulator.
Gabriella