OK, I got all the video clips and photo's in order, and was dropping overlay titles on the Text track by copying and pasting a title.
Then, I reordered a couple of clips, and now, when I paste a title on the text track, it splits the video track below and it and moves the video apart by the length of the title.
I guess I must have hit something to cause the insert mode to change - so anyone know what it was and how I get things back to how they were?
Thanks.