If you use custom cockpit camera configuration files, for example to allow your “viewpoint” to be outside of the aircraft, I’ve found the folder where they get stored:
C:\Users[Your User Name]\AppData\Local\Packages\Microsoft.Limitless_8wekyb3d8bbwe\LocalCache\SimObjects\Airplanes\asobo_nxcub\presets\asobo\nx_cub_advert\config\cameras.CFG
This example is for the Cub Crafters NX Cub, but you can find any of the other planes for which you used [CTRL-Shift-0 through 9 to store a custom camera cfg file.