Steve is having issues where his computer turns back on after he shuts it down. Leo says to look in your settings for "wake on LAN" and turn it off. It's a feature designed for IT networks to be able to turn on the computer remotely. You also want to be sure everything is shut down. There may also be a scheduled wakeup. Both features are in setup (BIOS). Turn on your computer and his F12. Once in the setup, go through the settings for those options and disable them. Could a hacker be turning it on? Leo says once it's shut down, nothing is running. So no, it isn't that.
It's often a good idea to label cables so she would know what belongs to what, but Joan shouldn't really worry about it. They're pretty much built to be plugged in without incident, as long as she's not trying to force it into a recepticle it's not designed to go into. It'll either fit or it won't. Many cables are also color coded, so she should make sure to check for that. To be safe, Joan could probably get a college or high school geek to set it all up. They'll know how.