Editing generated subtitles - split and merge

I used the generated subtitles (speech to text) which is a great feature, but I need to edit the generated subtitles.

But the generated text lines aren’t perfect, with words left alone or too much text for other lines.

What I want to do is to merge two lines into one, and sometimes split one into two. Is there a way to do this (except manually removing one and extending another)?

No, use keyboard shortcuts plus cut and paste text.

Which keyboard shortcuts?

The ones shown in the tooltips, menu item Help > Actions and Shortcuts, Keyboard Shortcuts web page, and forum documentation page Keyboard Shortcuts as surfaced through the forum search. It is extremely well-covered; all you need to do is look and help yourself.