I think someone has remote access to my computer. How do I check/fix it?
So yesterday I saw that I got logged out of Steam, which was odd because I'm always logged in, and after logging in, my Steam username was something different. At that moment, I didn't think much of it and thought it just might be one of my friends who has access to my Steam. Today, going a bit deeper, I saw Steam logins from USA, China, UK, Netherlands (VPN obv) for the past two days on my Steam. I immediately deauthorized all devices on Steam, but I'm concerned my whole PC might be compromised. One thing I can do is do a clean Windows install, but there are too many things on my PC (using it for the last 7 years), so I'd have to sort for hours and then go for a Windows reinstall. Is there any way to confirm if my whole PC is compromised or not?