Question: Why does Maple keep changing commands?

I want to graph a real-valued function e.g. plot y=x^2 from x=1 to 2.  There used to be a function called "plot2D". But it does not exist any more. When I call up the glossary or Help list, I get hundreds of plot-related functions - countourplot, loglogplot, etc - but not a plot for doing a real-valued function.  It is not under with(plots): 

The fact that every time I go to the glossary or search for functions the commands have changed, and that this has gone on since 2007, is the reason I have to keep asking the same questions over and over again. I never get the same answer twice.  For example, it used to be Diff(f(x), {x,3)) if you wanted to take the third derivative of f with respect to x. But that does not work any more. Now the command is diff or something, and I have to write out diff(f(x),x,x,x).

Does Maple automatically download updates to my computer with new glossary lists?

I know that some topics which used to exist, such as "simplify" under algebraic expressions, no longer exist.

The command "Coefficient" used to exist. Coefficient[6*x^4+7*x^5,x,5) would return 7, the coefficient of x^5.

This was and is an incredibly important command for me. Now, I have to compute coefficients of terms manually - i.e. by visual inspection. The command "Coefficient" no longer exists.