I am trying to copy select business processes from the EMB37 model to a different version, but when I duplicate, it won't allow me to change versions, Any thoughts on where I am going wrong?

Paul

If the new version is derived from EBM37 it is easy enough to copy it. Actually that is the only way a change can be made if the new version is the version you are using.
If the new version is not derived from EBM37 you can consider to use session tgbrg1200m000, Copy Version Data to Other Version.

As you didn't state your approach or were very specific on the situation I can't suggest anything else than this. Good luck!