Update Your Computer and Scan
No seriously, stop pressing snooze on that update button. The single best thing you can do for your computer, and all the computers you are in charge of is to turn on auto-update and forget about them. They are significantly more secure when they can receive updates on time. If your computer isn't updated, restart now and apply updates, this course can wait. While you're doing that, update all the computers you are responsible for. You're a tech person now so get ahead of your family members breaking their internet boxes.
You always like to assume you don't already have malware on your computer but if you are working off of a shared computer, there are no guarantees. First, ensure that Windows Defender is enabled. If it isn't, turn it on. Once again, do this on as many computers as you are responsible for. I don't really recommend adding 3rd party antivirus solutions these days because Defender is so good (notably Defender does not uninstall spamware or other programs that are annoying, just not malicious). If you believe that your computer has some sort of malware on it but Windows Defender isn't removing it, run MalwareBytes and see what if anything is detected. If MalwareBytes and Windows say you're good, you're probably good.