How to add subtitles to iMovie

Re: "How to add subtitles to iMovie"

For adding simple subtitles you can use the "Titles" feature in iMovie:

Eg: There's a short third-party (non-Apple) tutorial (2.24 min) on YouTube: "How to Add Subtitles in iMovie on Mac – Easy Tutorial"

https://www.youtube.com/watch?v=YZCg8U_Crk4

Else: If you want something more creative or more professional:

There's another longer Third Party (non-Apple) video (13.59 min)

How to: "Create Custom Video Text Captions For iMovie With Keynote"

https://www.youtube.com/watch?v=mAv0x06toiU

The useful resource: iMovie User Guide for Mac - Apple Support

doesn't mention subtitles.

Yet it does explain how to use the Titles feature:

Add titles in iMovie on Mac - Apple Support