I can see where you might be confused because of the terminology used. I am used to calling everything a “key”, but I should have used the terms that the 2500 manual uses, and you wouldn’t be so confused.

When I said “any key”, I meant any key or button. You can teach every square LCD touch key on any screen, and also the hard buttons, except for More, Light, and Commander Off. This means you can teach a command, if you wanted to, to any of the component buttons, the system control buttons, plus all the other hard buttons (except as noted), as well as the keys on the touch screen display. You should have been able to teach to the OK key also. It sounds like you may have already learned a command on that key, so you can delete the learned command and learn something else, if you want to.

The AMP key on the Elite remote is used to tell the REMOTE, not the receiver, that you want to select a mode. Since you have already taught the infrared commands to the 2500 by pressing the keys on the Elite remote after pressing AMP, you can directly access the modes without having to press the AMP key, which you couldn’t have learned anyway because it doesn’t emit an infrared command.

Clear?