I recently installed Windows 8.1 from a USB drive. In order to boot from the USB drive, I had to disable secure boot in the BIOS and switched to Legacy boot mode (from UEFI boot mode).
After the installation finishes, I no longer need to boot from the USB drive so I want to switch back to secure boot (UEFI boot mode) but then Windows wouldn't boot.
What did I do wrong? Do I need to install Windows again?