USB booting to installing Linux on a new Lenovo laptop

Change the BIOS from UEFI to legacy. When I did that, the USB appeared in the boot menu when restarting my computer.

You probably just need to disable Secure Boot, so the linux installer is allowed to boot.

You can check whether this is enable by running this in a Windows terminal (e.g. powershell):

Confirm-SecureBootUEFI

If you have it Enabled, go to the power off options and while holding the Shift key, click on Restart. Then select 'Troubleshoot', 'UEFI Firmware Settings'. You can then choose to 'Disable Secure Boot'.

A full guide on 'Installing Ubuntu on a Pre-Installed Windows 8 (64-bit) System (UEFI Supported)' can be found here.

I have the same laptop and do have Ubuntu installed on it.

All I had to do was navigate to the "Restart" area in BIOS and disable OS optimised defaults. Navigate to the "Startup" area and ensure that the F12 boot option is enabled. Exit saving changes. Check if you have the authority to do this.