Deactivating the current version of a port and activating a different version

[Barrie Stott]

I ran 'sudo port upgrade outdated' and macvim was upgraded as part of this. I suspect that this new version is not working as it should but, being timid, I accept that it may be as a result of something else. With that in mind, I would like to try my previous version to see if the problems I am now experiencing go away.

As I see it I need to do two things: deactivate the working version of a port and activate a different version.
I've scoured the Users Guide regarding this but without success so if anyone can help I would be very grateful.

Barrie