Hi,
A project shared from iMovie and then played on QuickTimePlayer will play through to the end and stop (unless you have it set for automatic looping, that you said you didn't want). It will not jump to the beginning and stop. If you have black frames before the first title and after the last title then the black frames will display when the movie is stopped at the beginning or end.
To work around this, import the shared out movie into a newly created iMovie project. Trim off the black frames before the first title and after the last title. Then share out the project. The newly shared movie should now play to the end and stop, with the end title displaying. When you click to play it again it will jump to the beginning, displaying the beginning title, and then moving through the movie to the end where it will stop with the end title displaying.
-- Rich