By default, Final Draft will launch with the most recent files you had open when you last quit the software. If you had multiple files open, it may show you the incorrect file rather than the one you're hoping to continue working on.
You can go to File > Close on each file that you don't need open, and that will stop FD from reopening those specific files.
If you wish to disable this feature entirely, you can go to Help in the menu bar, select Welcome to Final Draft, and in the new window that opens, uncheck the option reading "Launch With Most Recent Files":
If that is disabled, Final Draft will open to the Welcome screen every time unless you open a specific file on your computer.