To disable signing policy and install unsigned drivers on Windows 10 you have to change boot options. F8 menu in booting is not working any more.

You have to boot it to disable driver signature enforcement. This will disable enforcement for one time driver installation. There is a lot of options to reboot system in “Advanced startup” mode:

  1.  Go to Settings -> Update & Security -> Recovery -> Advanced startup -> Click Restart Now:
    settings menu advanced start-up
  2. Click Start menu -> Power Icon -> Hold SHIFT and click Restart
    shift+restart advanced start-up
  3. In command line put:
    shutdown /r /o 

  4. Boot from installation media (CD, DVD, USB Pendrive) and choose Repair your computer:
    advanced start-up from bootable usb pendrive
  5. Boot Troubleshoot from manufacturer recovery (sometime you have to choose Start-up repair to show Start-up  settings)
  6. Enable Legacy boot options menu and press F8 when system start-up
    1. Run cmd as administrator
    2. Put in command line to list all vailable systems:
    3. copy identifier and replace {default} with current or your id like {123ffff….}
      bcdedit /set {default} bootmenupolicy legacy
    4. To recover normal booting put command:
      bcdedit /set {default} bootmenupolicy Standard

When you boot Advanced start-up click in order:

  1. Troubleshoot:
  2. Advanced options
  3. Start-up settings
  4. Restart
  5. Click 7 or F7 to Disable driver signature enforcement:

Manually drivers installation

  1. Disable drivers signing policy if it necessary
  2. Go to Device manager:
    1. Start -> Run: devmgmt
    2. Right click on start -> Device manager`
    3. System -> Device manager
  3. Right click on device which you want to install driver and Update Driver Software:
  4. Click Browse my computer for driver software
  5. Let me pick from a list of device driver on my computer
  6. Pick Show all devices
  7. Click Have disk and browse for any .inf file in drivers directory, windows will find correct driver by pid and vid:
  8. Choose correct device
  9. In Windows security warning pop-up  window click Install this driver software anyway
  10. Done:

Permanently disable driver signature enforcement

Run cmd as administrator and put:
bcdedit /set testsigning on

It will allow install any drivers and will enable watermark.