Keyboard shortcuts keep getting reset on startup (Win 10)

It seems that I have been able to resolve this problem—and since nobody addressed this specific issue, let me tell you how I did it.

It turns out that Windows 10 (and some previous versions as well) has separate language settings for the lock screen. When you install your own custom layouts, Windows sets up its own counterpart for the lock screen—probably to avoid problems with non-standard input.

So whenever you bring a computer from sleep, hibernation, screensaver or the lock screen, it switches between those two sets of layouts: your custom ones and it's default counterparts. But if they don't match—i.e. you have your own French keyboard layout, and the lock screen has the MS French keyboard layout—Windows simply resets the layout shortcuts until restarted.

The solution, hence, is to copy your custom keyboard layout settings to the lock screen. You can do this in the Control Panel: Control Panel → Time and Regional Settings → Language → Advanced Settings → Apply language settings to lock screen…. Be sure to select both options in the prompt window that follows!

This has worked on all of my Windows 10 computers.