Make sure to add the new Code Set Style to the template being used to create new drawings.
This way it will always be present in every new drawing created.
The template used to create New drawings is set by the QNEW variable which can be specified in OPTIONS.
Options > Files Tab > Template Settings > Default Template File Name for QNEW.
To import the code set into other drawings run the _ImportStylesAndSettings command or drag n drop between dwg's.
C3D 2018.1
C3D 2016 SP4
Win 7 Professional 64 Bit