Windows 10 changes UEFI boot order every time

I also faced the same issue that Windows 10 (Education) automatically, on startup, moves the Windows Boot Manager EFI entry to the top again. If I changed it, after restarting with Windows, the next boot skipped Grub and directly booted into Windows. This is how I sovled it:

I would recommend the tool EasyUEFI http://www.easyuefi.com/ to view and change some EFI related settings.

1. Open the tool and select Manage EFI Boot Option

2. Take a loot at the exiting entries. The two important ones for me are:

   Description:Windows Boot Manager
   GPT partition GUID:{505E666C-00CD-4654-BB80-FBD2C6F9F191}
   Partition number:2
   Partition starting sector:923648
   Partition ending sector:1128447
   File path:\EFI\Microsoft\Boot\bootmgfw.efi
   

   And:

   Description:Ubuntu 16.04
   GPT partition GUID:{505E666C-00CD-4654-BB80-FBD2C6F9F191}
   Partition number:2
   Partition starting sector:923648
   Partition ending sector:1128447
   File path:\EFI\ubuntu\grubx64.efi
   

3. The next step is to make sure that Windows does not use its own bootmgfw.efi file again, but rather grubx64.efi. To do so, don't move an Ubuntu EFI entry to the top again (i.e. that's the problem we have), but just set the file path for the Windows Boot Manager to \EFI\ubuntu\grubx64.efi. You can also do this from the administrator command line:

   Bcdedit /set {bootmgr} path \EFI\ubuntu\grubx64.efi
   

   Now, Windows should not change the EFI settings anymore and on every boot, GRUB is the default. As GRUB ideally already identified your Windows OS, it also contains its value in the grub settings.

I had this problem and solved it by setting a password in the UEFI/BIOS for accessing it. Apparently, when a password is defined, windows can no longer make changes in the UEFI/BIOS. The computer is a Lenovo.

My Sony laptop was also changing the boot order upon start-up. Another alternative that worked was to use EasyUEFI to disable the Windows Boot Manager EFI entry.

This left the existing Ubuntu boot option as the highest active.