The biggest problem here is that computers are complicated !!
That is a fact. Windows and Linux GUIs (Graphic User Interfaces) are simply means to make the complicated easier to use, so that, world-wide, not just experts can use a computer.
The computer itself is just a small part in a system of hardware, software, cables, and other stuff necessary to allow you to use your "computer" to write letters, print them, play games, use graphic programs, etc, etc.
A computer system is a tool to extend your capabilities, but when we then go on the internet, the situation gets worse, because a tool that you are using privately is now hooked up to the whole world. It then becomes vulnerable to attack from anybody and everybody who uses technology for criminal purposes. (A hammer is just a tool, but if a crook uses a hammer to bust your door down, so he can rob you, then you think of a hammer differently) .
Some time ago (I'm not sure when, possibly with the introduction of Vista) thousands of computer users suddenly complained that their computer wasn't working correctly. The reason ?: till then, Microsoft had delivered Windows with all "factory set" safety settings defaulted to OFF. They then changed their policy to say factory setting default is now ON, as they had noticed that too many users were ignoring the advice to reset to a secure setting.
(Own up - how many of you have electronic devices with a factory set pin-number 0000 and don't bother to change it ??)
As others have pointed out, it is important to update your computer software.
And as others have also pointed out, you can decide whether this should happen automatically, or whether you will just receive a pop-up saying that updates are available, and you decide when the update will happen.
Bob