virtualbox.org

HOST --- Windows XP Professional:
GUEST --- N/A, but Ubuntu

I would like to export and import appliances from a dedicated folder that is different from my mydocuments folder.
I did not notice how when I read through the manual and the vbox manage commands.

Is there a way to change this default?

Why are you using export/import at all? If the VM was created by VirtulaBox v4 or later then why not just copy the VM folder?