Changing key bindings in xcode

I have quite a simple problem: a good portion of the key bindings i set in Xcode simply don't work.

Example: I set "code sense select next placeholder" as command+E on my desktop..yet on my laptop when I set it to that, it just beeps when I push command+E.

Second Example: I want to change the default key for popping up the class/method list [currently control+2], but it won't let me change it to command+2, or most other things for that matter. I've had so many problems I don't think ALL of the conflicts can be system/xcode presets that are unchangable.

How do I force Xcode to use the key bindings I want?

alternately: How do I see which programs are keeping Xcode from recognizing the key bindings I set?

Thanks,
Nick