Switching to UEFI mode can't normally be done in Windows. When the computer firsts boots you should see an option to enter setup. Common keys are F2,F10,F12 and DEL. The layout of UEFI will be different, but you'll want to look for boot or mode and make sure it is NOT set to legacy. The terminology can vary between systems as well
You can also just google "<your model enable UEFI boot"