Sketch save on verify/upload version 1.6.1

Hello,

I'm having problems with sketches being over-written.
I pull up a sketch, make some changes, then decide I don't like them, so close the sketch without saving the sketch, hopefully to leave the original in tact, as was.
It's probably something daft, but applies since upgrading from 1.0 to 1.6.1
I have unchecked "save on verify/upload" in preferences, restarted Arduino, checked that the new preference is in place, pull up a sketch, make changes, verify and upload, then close without saving - the changes are there when I re-open the sketch. I had a look through the preferences text file but can't see anything amiss.

How do I stop this?

Thanks