If your text fields are changing then you have a default, or a rule somewhere that is changing them. Is there a lookup by ID? You would need to turn off this update or add conditions to make it smarter and only update where you want it too.
When inserting you have the default values you can configure, also pay attention to the top of the window where you can set the default for all fields or just the new ones. This is not always obvious but you may have some checked to always update which is typically what you do not want.
You should be able to configure the functionality you describe, you may just need to do some simpler tests and master the setup.
If you need some specific help or training, you can purchase support credits at http://www.qdabra.com, and one of our MVP's could assist you personally.