My computer reverts back after reboot!

This is a sign that the CMOS battery need to be replaced.
Shut down your system. Locate the CMOS battery on your motherboard. Uninstall it & get a replacement battery. Install the replacement battery & power up your system. Go to BIOS & apply your settings, the save & exit.

Hi, I think your computer have a software for freezing the system, one software I know is deep freeze, which reverts back the system after a reboot. Try to locate if your computer have one, and terminate or uninstall it. Or may suggest formatting your computer to enjoy what you like to do in your computer, just like having a fresh one computer. Thanks and hope I can help

that is Last Good Configuration   it happens when you have a Blue Screen Of Death which you may not see but is caused from having an incorrect driver installed for your graphics card or audio etc  you may have installed for the wrong operating system  or windows updated for you because you have your setting set to download and install updates automatically    change that to download and you will decide when to install updates   go to safe mode  (F1 or F8, or esc when booting up) and roll back the driver in device manager for the driver that you may suspect is wrong