Computer Help and Support

Assuming that you change things like default passwords, ensure that the built-in protections are enabled, etc.

Of course, that doesn't apply if the copy of Windows being used for the install isn't legit and is corrupted or infected with malware, etc. Which, in this case, sounds like a possibility.

Unless there was software added after the installation, a recovery install would likely just produce what you're already seeing. It usually writes a factory image to the hard drive from the recovery partition.

There are tens of thousands (or more) of settings in Windows. Going through them one-by-one would be a waste of time. Find some good guides online for how Windows 10 security works and start there.

Example, which also includes network security suggestions: https://www.tomshardware.com/news/security-mistakes-to-avoid

Another (video): https://www.pcworld.com/article/3602672/what-you-need-to-know-about-windows-security-in-windows-10.html

One that's more in-depth, though it's a bit more targeted to business customers: https://www.zdnet.com/article/the-windows-10-security-guide-how-to-safeguard-your-business/

Lots of others out there.