Some users have recently had their accounts hijacked. It seems that the now defunct EVGA forums might have compromised your password there and seems many are using the same PW here. We would suggest you UPDATE YOUR PASSWORD and TURN ON 2FA for your account here to further secure it. None of the compromised accounts had 2FA turned on.
Once you have enabled 2FA, your account will be updated soon to show a badge, letting other members know that you use 2FA to protect your account. This should be beneficial for everyone that uses FSFT.
right click file/folder in question, go into properties of the item and use the security tab. hit advanced, hit owner tab. select a group that you want to take ownership (administrators usually) and hit okay.
put simple file sharing back on when you're done, if you didn't know it was there, you shouldn't be messing around with it.