[OS X Emacs] Aquamacs Meta key

[7stud]

Hi,

About every half hour when I'm using Aquamacs, I (mis)type a key sequence, and my Meta key, which is the default Option key, changes to "Option for composed characters", which can be seen in in the Auqamacs menu bar under:

Options > Option, Command, Meta keys > Option for composed characters

Thereafter, every time I hit a Meta key sequence, e.g. M-p, a mathematical symbol, e.g. pi, gets entered into the buffer--rather than the emacs key sequence doing the expected operation.  This is very irritating.  Is there a way to permanently set the Meta key to my Option key? I don't want anything I type ever to be able to change which key is the Meta key. 

And, I would encourage the Aquamacs implementers to remove this "feature" forthwith.   Do you have any idea how frustrating it is when someone is trying to learn emacs, and the Meta key randomly changes, causing emacs key sequences not to work as described?? Do you think that beginners are going to be able to figure out why certain key sequences don't work, i.e. that their Meta key suddenly stopped being the Meta key? 

Thanks.