This illustrates the puzzle:

Shouldn't MEP be able to intelligently deal with such a minor adjustment? Or have I overlooked (or forgotten!) something basic please?

Later I'll check it in pevious versions.

Edited a few minutes later: It's clearly something to do with those sound clips (microphone narrative I added) because when I temporarily deleted them all I could then correctly alter durations of the photos.

And after another few minutes... When I dragged that section of audio objects from track 2 into track 3, all was well. Anyone know why?

--
Terry, East Grinstead, UK