I will show you a generic way on how to find the place in the OS registry where stores all the settings related to SAP GUI.
The basic idea is to export the registry as a snapshot before SAP GUI setting is changed, let's say before change snapshot. And change some settings or do something via SAP GUI, and export the registry again let's say as a after change snapshot. Compare the two, the difference what you are looking for.
You can use File->Export to export the node HKEY_USER and its children:
Then change some settings in SAP GUI, and export the after change snapshot.
I use the standard tool available in command line FC ( file comparator) to try to get the difference between the two.
it failed to finish the mission:
So I choose a more professional tool: Regshot ( You can download it from Google )
You can create two snapshots and it can automatically generate the comparison report to you: