Hi,
As far as I know, you can't stop the text scrolling off the screen.
(I am using v2.41 but I think 3.0 works pretty much the same if I remember.) Anyway these comments relate to 2.41.
You can get it to stop, in a roundabout way, by extending the text overlay beyond the end of the sequence line.
In preview you will see the film finish with a blank black screen with the scrolling text stationary. By adjusting the position of the overlay you can get your text to stop at any point. You can neaten the effect if you fade out the sequence if you want.
The problem now is that the saved film stops along with the text and then disappears straight away to a blank screen.
So, before you try this. Save your project.
Now remove everything except the last clip/s over which you want the text to scroll.
Add your scrolling text overlay.
Slide it beyond the end of the sequence line.
Review the sequence and adjust the overlap to get it to stop where you want.
Now save this as short avi clip to your PC.
Reload the project
Reload the avi back to the media list.
You can now place it at the end of your sequence and continue to add to it.
Nat