You can use the following shortcuts to manage your narration.  

Shortcut

Action

Delete

Delete Selection

Ctrl-Z

Undo

Ctrl-Y

Redo

Ctrl-+

Zoom In

Ctrl--

Zoom Out

[S]

Stop

Space

Play/Pause

Home

Go to the beginning of the clip (selection)

End

Go to the end of the clip (selection)

Arrows

Move cursor position backwards or forwards (small steps)

Ctrl+Arrows

Move cursor position backwards or forwards (bigger steps)

Ctrl+TTrim audio/video
InsertSilence selection or Insert silence