Angels have the Phone Box
Please create a restore point before you do anything else.
I would advise leaving Charter's F-Secure for another day....maybe never. I can recommend Avast! Antivirus Free. We have confirmation here in the forum that it works well with W10. If you decide to install it, please only install the items I show highlighted below, and use the custom install so you can also skip the optional Google Chrome:
The combination of Malwarebytes Antiexploit Free (active) and Malwarebytes Antimalware Free (passive) works well with Avast.
Another viable option is to continue using Defender, but then add the paid version of Malwarebytes Antimalware, and the free version of Malwarebytes Antiexploit.
Good job! And, please be sure to give a rep (thumbs up) to @essenbe, who saved you from an in-place upgrade!