It blocks every attempt to modify any file anywhere. I give Steam and all its subsidiary .exes permission and then it says that there is no permission to modify 'Documents'. I just bought the darned machine to game with and it is freaking driving me nuts. Any suggestions on where to go to fix this?

Turn Defender off, and use something else, would be my suggestion to be honest. There are plenty of other free security solutions that do as good a job, and mostly a better job, than Defender so why bother jumping through hoops with it? Avast, Avira or even Kaspersky Free for example...

Actually, I did not google because I used it as an excuse to come back for a visit. So, now I googled it and it is fixed - ''check aps and files'' off.

Excellent! Glad you are sorted now, but hang around for a bit anyway :-)