Download ccleaner:
http://www.piriform.com/ccleaner

It's free. Use it after every browsing session.
It removes everything....whether you know something is turned on or not.
It will also straighten up the registry, edit start menu programs, and keep the machine running smooth and fast.

I understand the value of what you're talking about but, so long as you shut the computer off when you're done with it,  and you have a log-on code known only to you so that the desk-top and web browsing functions are available to no-one else, why is that not sufficient protection?  That's what I do and I'd really like to know if there's a flaw in my logic.

refers to...  Googling it brings up all sorts of Real Estate Ads...  no one has the P/W & I use the In Private setting which is why this was upsetting.   I shared because this was an unanticipated problem...  caught me by surprize.  
I thank everyone for the thoughtful advise.  There is no room for careless or sloppy in my hobbying...  little slip ups are bound to happen but I'm sure going to fight them & minimize the ones I can.   I was alone when I found it...  I stuck with it until I had solved it.
Little mistakes plant the seeds of doubt which can build to suspicion...  then all bets are off!  I repeat, One can never be too careful.
HV

I have my web browser set to clear all history every time I close my internet down... yea, I have to type in the full web addresses EVERY time I get online, but there is never any browsing history.