How can I set my preferred game controller through the registry?

Windows allows a “preferred” device to be set as the primary controller. What registry key is responsible for this? I want to change it through a batch script rather than opening this dialog every time I want to swap controllers.

This is a limitation of some games which only uses the preferred device.

I don’t believe this information is kept in the registry. The reason is that
Windows 10 does not keep this information between reboots, so it is clear that
the information is kept in memory.

I have seen the advice given by gamers to never turn off the computer, but only
sleep, because this conserves the order of the game controllers and the preferred
one.

For keeping the order of game controllers, the manual solution is to verify the
order after each boot. If Windows has shuffled the order, the advice is to remove
the out of order controllers and add them back in in the required order.
Added controllers are always added to the end of the list.

One gamer has had enough and has written the package
devreorder,
which is still being maintained.
The order is specified inside a file named devreorder.ini, using the exact
names as listed in the Game Controllers dialog.

The readme file of devreorder is very detailed and contains a lot of useful
information.