I don't believe there's a way to do this, somebody please correct me if I'm wrong:
It would be great to be able to set a default mode, master type, exclusions, etc. in a showfile, and have all new subs created with those properties.
Example: all new subs would be Additive, Intensity Master, exclude from record (the settings that I find myself selecting on almost every sub I create).
Perhaps this belongs in user settings, alongside record defaults?
There's no user default sub settings, but you can do [Sub] [Sub], select all your subs, then change the properties. That should change settings for anything selected.