In a Project, select "Review Mode" (top).
In Review Mode, toggle the "New" switch off (top). This ensures that you're seeing all documents, not only new documents.
For a file you'd like to rename, select the "Magic button" (right of the file name).
Select the "✓" to save the new file name.
And you're done!
**Note: Changing file names is global, so renaming files will also affect the file names in Drive. This benefits continuity within Truss for cataloging.