the CSM option in bios is disabled -how do i enable it?

Computer Type: Laptop
System Manufacturer/Model Number: HP Envy 17
OS: Win10 Home x64 - 1809
CPU: Intel Core i7 4710HQ @ 2.50GHz
Motherboard: Hewlett-Packard 2291 (U3E1)
Memory: 12.0GB Dual-Channel DDR3 @ 798MHz (11-11-11-28)
Graphics Card: Intel HD Graphics 4600 (HP)
Sound Card: Realtek High Definition Audio
Screen Resolution: 1600 x 900
Mouse: Logitech MX510
Hard Drives: Samsung SSD 860 EVO 250GB (SSD) / Western Digital Black 1TB (SATA)
Internet Speed: 10 / 200
Browser: FireFox
Antivirus: Windows Defender / Malwarebytes 3.0

Computer Type: PC/Desktop
System Manufacturer/Model Number: HP Envy 750-530
OS: Win10 Home - 1809
CPU: Intel Core i7 7700 @ 3.60GHz
Motherboard: HP 82F1 (U3E1)
Memory: 16.0GB Dual-Channel Unknown @ 1196MHz (17-17-17-39)
Graphics Card: 3071MB NVIDIA GeForce GTX 1060 3GB (HP)
Sound Card: Realtek High Definition Audio
Monitor(s) Displays: HP 24W / HP 23E
Screen Resolution: 1920x1200
Keyboard: Logitech MK545
Mouse: Logitech MX510
PSU: 500 Watt
Case: HP Envy
Cooling: Standard
Hard Drives: SAMSUNG 840 250GB (SSD) / 2 Western Digital Blue 1TB (SATA)
Internet Speed: 10 / 200
Browser: FireFox
Antivirus: Windows Defender / Malwarebytes 3.0