Vicky, your current issue has nothing to do with the UEFI issue in this thread.
> I then select windows 8 and use windows 8.
Technically you only had to do an in-place upgrade to Win10. This reliably ;-) overwrites Grub.
Officially, this has been possible free of charge for up to 1 year after the release of Win10. With several time extensions.
Then you can install an up-to-date Linux distribution in dualboot.
But if you can boot normally from a USB stick, you don't have the problem in this thread anyway and can install Linux as the only OS.
Vicky, your current issue has nothing to do with the UEFI issue in this thread.
> I then select windows 8 and use windows 8.
Technically you only had to do an in-place upgrade to Win10.
This reliably ;-) overwrites Grub.
Officially, this has been possible free of charge for up to 1 year after the release of Win10. With several time extensions.
Then you can install an up-to-date Linux distribution in dualboot.
But if you can boot normally from a USB stick, you don't have the problem in this thread anyway and can install Linux as the only OS.