When saving a script for the first time:
- Choose File > Save and the standard Save As dialogue appears;
- Navigate to the location where the file is to be saved;
- Type the name of the script into the Save As name field;
- Click Save.
Every subsequent time you want to save your file, you can choose File > Save or use the Save button in your customizable Toolbar:
You can also press Command + S (Mac) or Ctrl+S on your keyboard and Final Draft saves the file.
On Mac only, in addition to saving your script, you can also create a back up document:
- Choose File > Backup. The standard Save dialogue appears with the file’s name and today’s date added;
- Navigate to the folder where the backup will be kept;
- Click Save.
The script will be saved and the month, day and year will be appended to the end of the file name.
To read further about saving and backing up your work and customizing your Toolbar:
https://blog.finaldraft.com/saving-and-backing-up-your-screenplay-files