I have another question. I followed the 747 manual for landing by switching off tha A/T before touchdown, then turned the Reverse Trust on after touchdown and in spite of that, the aircraft continued to go full speed while I stepped on the brakes and turned the reverse trust off.
Find some where with a lot of room like the taxi way or the runway. Go to external view and move in so you can see the engine nacelles clearly. Experiment with engaging disengaging Reverse Thrust. You will be able to observe what works and when.
Awkward and involved I know, but it will help you figure out your system.