C:\USERS\Default is the "Default" Profile used to spawn new profiles.
Any Changes here will be reflected in newly created profiles.

REG.EXE can then be used to load/unload each profile on the PC including default and insert any needed registry changes.
Files could also be copied as well.

I did a quick google search and here is one exampe -

I have not checked to make sure this post is the best way or has all bases covered.
I have built my own tools and scripts to handle this in the past....just don't have any handy.
I found this method very handy...this way when I had to change a Per User Setting, it was once and done for everyone.

(SILLINESS ALERT! - In Regedit, HKEY_USER\.DEFAULT is NOT related to the Default Profile. This is the HIVE for the SYSTEM Account...Why they called it .DEFAULT is beyond me...)