I would suggest that if you can, you physically remove the other drives, at least the windows drive or disable it in the BIOS again, if you can. If you have a laptop, not so easy to do. The reason for this is so that you do not accidentally overwrite system or data on the windows drive. I don't use Kubuntu so I'm not familiar with its installer but I can tell you that the installer for Ubuntu (Ubiquity) when installed in EFI mode will install the EFI boot files on the first drive it finds which is your windows drive which already has an EFI partition. And as suggested, disale Legacy/CSM boot before you install.

It certainly appears that your original windows 10 now windows 7 if in EFI mode because the drive windows is on is a GPT drive and according to Microsoft their windows systems won't install on a GPT drive unless they are EFI. The info you posted earlier on the hard drive on which you have Ubuntu shows it is a Legacy/msdos drive and Grub on a Legacy drive will never boot windows in EFI.

For future reference, if you use the vi text editor you need to save it properly as explained above or you will not be able to open it. It will show messages with instructions and basically you need to enter: :recover on the bottom line and hit Enter and you will get options of what file name you want to save as with a number for each option, type the number and hit Enter. I've done this more than once and I don't really know what the .save file was you deleted. Generally it is a good idea to check to see if you have the original file (sources.list in this case) before you delete the .save file.

Good luck with Kubntu.


Simply type :recover on the last line and hit the enter key