Hello,
right now only some preferences are stored. You can see by opening regedit and navigate to:
HKEY_LOCAL_MACHINE\SOFTWARE\WinFIG
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Version 4.x and later stores the settings in: HKEY_CURRENT_USER\Software\AndreasSchmidt\WinFIG
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It always stores the last used values as defaults. Probably you are right and it would be nice to store grid, magnet, units, zoom, page size and orientation too. I will see if I have some time to do it.
The GhostScript path is determined by looking into the following registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\AFPL Ghostscript
Then WinFIG picks the first entry it finds. If you have 8.13 and 8.53, it would pick 8.13. This is perhaps not the most elegant way, but I did not really consider machines with more than one GhostScript on them.
Right now you can probably only remove the 8.13 installation. Actually I would do that. Or is there a special reason why you still need the 8.13?
Perhaps it would work to install 8.53 and then 8.13. This could place 8.13 after 8.53 (but I did not try). In that case WinFIG would choose 8.53.