I have a Lenovo Yoga 720 laptop with Windows 10 installed. I was attempting to install Ubuntu 18.04 as a dual boot option.
I was able to install Ubuntu successfully, but encountered some difficulties in that during the boot up process, I was not seeing an option to choose between the two OSs. I had to press F12 manually and select from one of the choices to boot into either Windows 10 or Ubuntu 18.04.
I think this was because I had installed Ubuntu in legacy mode, but later found out that I should have installed it in UEFI mode instead.
To start over, I removed the Ubuntu partitions using the Disk Management application in Windows.
Now when the boot mode is set to "Legacy Support" (boot mode: legacy support), I either get an error and go into GRUB rescue mode (I tried Boot-Repair by loading Ubuntu using a live USB as well as the program Dual-boot Repair Tool to no effect) or have to press F12, after which I go to this screen. From there, I have to choose the second option to load Windows 10.
On the other hand, if I set the boot mode to "UEFI" (boot mode: UEFI), I can load Windows without any issues. In this case, on pressing F12 and loading the boot manager, I see this. As you can see, there is only one option (Windows Boot Manager).
Can someone explain is happening here? Why do I not see the second option when the boot mode is set to "UEFI?"
I also wish to know how I can remove the additional option ("SATA HDD : SAMSUMG MZ......") from the Boot Manager when the boot option is set to "Legacy Support," so that Windows loads automatically in this case too without having to press F12 and choosing the 2nd option from the Boot Option Menu?