Thanks frmax. This was the problem. It is in Vegas Pro 18 and was enabled by default. I was really pleased to open VP18 with nice sharp graphics and text rather than the somewhat fuzzy display of earlier Vegas Editions. Checking VP17 I note this was an experimental option and on my installation not enabled. The misplaced Render options box is only a minor inconvenience having DPI enabled, one I can put up with for the better display!