Not all of your customer defaults will be used When create a new part. This because there are part and session settings in the customer defaults. If you use the blank template NX will take all the defaults in the new part.
The other way is the edit your model template add there all the changed settings. If you the start then a new part nx will take all the settings of the template part into the new part (creates a copy of the template part)
Ruud van den Brand Pre-sales NX CAD cards PLM Solutions