There is no registry key that I know of - but that doesn't men there isn't one.
There are keys for special symbols - East (E), West (W), degrees (°), etc.
As far as I know it is only controlled in the object script.
You will need to open the object and go to the 'Compatibility Options' (version 16 & 17 or 'Details' in older versions).
There you can change the defaults - it will change to a 'Custom' value.
You will need to do this for every door and window and save the library part.
The problem is if you are using Graphisoft or 3rd party windows then these will be reset if you ever update them.
One of the forum moderators.
Versions 6.5 to 25
Dell XPS- i7-6700 @ 3.4Ghz, 16GB ram, GeForce GTX 960 (2GB), Windows 10
Dell Precision 3510 - i7 6820HQ @ 2.70GHz, 16GB RAM, AMD FirePro W5130M, Windows 10