The Before shot:
First CLOSE iMovie
Go to the finder and “Show Package Contents”
Navigate to Contents/Resources/English.lproj and do a “Get Info” on TrailerStrings.strings. Add Read/Write to your user to the permissions list.
You will also need to add READ WRITE permissions for the Contents folder, the Resources folder and the English (or whatever language you are using) folder.
Add Opens with TextEdit if you think you will do this more than once.
Edit the Credits Line being sure to leave the underbar “_” there
The After shot:
(I am sure you can change everything in that file, that is text, but BE SURE to keep a backup and don’t change the special characters)