Hmmmm. Another poster recently mentioned an issue with titles not centering. It possibly is related to the recent OS and iMovie updates, but don't really know.
I would retry deleting preferences again, as sometimes a second effort is successful.
Also, try creating a new project and see if the problem replicates there.
Another procedure that may help is to open iMovie in a new library. To do that, close iMovie and then open it while holding down the Option key and selecting to create a new library in the box that appears.
Try different titles and see if the problem appears in all titles.
As a workaround, when you come a point in the text line where your want to end the text and continue on the line below, when you reach that point try pressing the return key on your keyboard while holding down the Option key.
You can also create your title on a transparency background with the Preview app on your Mac. Then drag it into iMovie and use the Picture in Picture feature to overlay it onto your video or onto a background clip. To make a transparency screen, put a duplicate of any random photo on your desktop and double click on it to open it in Preview. In the Preview app do an Edit/Select All, Edit/Delete. If prompted to convert to PNG, click yes. That will leave you with a blank transparency screen. Then go to Tools/Annotate/Text. That will create a text box on the transparency screen. Choose your text font, color, and size from the text dialogue box (the letter A in the toolbar at the top of the screen). Type in your text title. Save. Drag into your iMovie project. Overlay it with the Picture in Picture feature. You will be able to position it wherever you want. Sounds complicated but after the first time it will be easy.
-- Rich
