Hopefully (and written from memory)...
Open up a midi file, Right click on a Track so as to bring up Track Properties and then click on Instruments.
You should see the page that lets you map midi tracks onto instruments. You can select tracks 1-16 together and then select the3k instrument definitions (you may want to remap track 10 to "3k Drums" if thats the way the definition file is organised).
There is a tick box "Save settings for next session" (or similar). Make sure this is ticked. Then hopefully you can exit from this page, exit and re-enter Sonar, and the mappings will be remembered.
_________________________
John Allcock