Captions were something you could see in the preview but not work with. They now have a place on the timeline.
A CC track
A CC track sits above the tracks with one clip per caption at its exact timestamps. The active caption highlights as the playhead crosses it. Clicking a caption clip seeks to it and opens the Subtitles tab, and clicking the caption text directly on the preview does the same thing.
Splitting and trimming
Split and trim were hard to find and fiddly to use, so several things changed at once. S splits the clip under the playhead without you selecting it first. Trim edge handles are wider. The ripple and roll tools trim by dragging an edge only, not by dragging the whole clip, which is what made them feel unpredictable. Roll now shows ⇧N, which no longer collides with the snap shortcut, and the toolbar ripple toggle is labeled Ripple delete so it is clear what it does.
Cmd/Ctrl+K and the ? search also find the split and trim commands by keyword, so you can reach them without remembering a key.
How you'll experience it
Generate captions on a project and the CC track appears above your tracks. Nothing about existing subtitles changes, they just become clickable.