Are you supposed to remove ->
the metal racks when using microwave,
and the microwave glass plate when You're using the convection?
You can keep the glass plate in always. There are different opinions about keeping the metal racks in while microwaving.
I've been told that if you keep them in, the hooks that hold them fall off much faster (if you have a model with hooks).
You also have to be careful to make sure that the racks are not pushed against the medal of the oven, because it will start sparking.
I personally take out the racks every time I microwave.