See this article for information on Final Draft compatibility on various Mac operating systems: Which version of Final Draft can I run on which operating system?
If you have FD12 or 11, open Final Draft and go to Help > Check for Updates. If you're prompted to update, follow the screens to get the new build installed. Your scripts will not be affected by the update.
If you have FD10:
- Open Final Draft;
- Go to the Final Draft menu at the upper left;
- Choose About Final Draft to determine which version is installed. If you don't have FD10.1.1:
- Quit Final Draft;
- Go to your Applications folder;
- Drag the Final Draft 10 icon to the Trash:
- Download the FD10.1.1 installer from this page and run it.
Your scripts will not be affected by installing the newer build.