Changing the engineering units in Ansys classic 11

FE software is intinsically unit-less. It is up to the user to use consistent units when creating the model and the loadcase(s). It sounds like the writers have tried to be helpful in incorporating some sort of list - there is always the temptation to try to sell to the uninitiated. It's a recipe for wrong answers. You must understand the quantities your are dealing with and how they relate to one another - fundamental requirement of a trained engineer. Equally important is to have an idea what the answer is before you run the analysis - that way unexpected results prompt a check of the model to identify slip-ups in it's preperation.