How do I ensure a hacker is truly gone from my computer?

It sounds like you’re dealing with a pretty common situation. Once a computer is compromised, any saved passwords or accounts accessed from that device might be at risk. Even if you revamped your security measures after the infection, if those changes were made while still using the infected machine, the hacker might still have access. It’s essential to reset all accounts, especially the ones linked to any usernames or passwords shared with compromised accounts. Also, completely wiping your drives before reinstalling Windows is vital. Just a standard reinstall might not be enough, so consider doing a secure wipe next time.

Did you change your passwords before you reinstalled Windows? It’s best to reset everything from a different, uninfected device to ensure total security. Make sure to log out of all sessions from any device you used before the wipe, and reset those passwords again. Always be cautious, as any linked accounts might be vulnerable.

One tip is to change your passwords using a clean device only. Meanwhile, consider investing in security tokens like Google Titan or YubiKey to ramp up your 2FA game. These gadgets provide an extra layer of security, and users often notice a significant drop in unauthorized access attempts after making such upgrades.

Classic case of adaptability; hackers might have snatched your passwords and tokens. Be sure to visit every site you use and terminate any lingering sessions. Also, if you didn’t do a secure wipe before the reinstall, now’s the time to consider doing so and starting fresh.

Just to add a note, if you didn’t perform a secure wipe before reinstalling, you might want to rethink your process. You'll likely need to reset any accounts accessed previously on that device after doing a thorough wipe and reinstall. And yes, keep your new passwords safer from any future threats.