Edit Toolbar
These tools perform the same functions as those accessible through the Edit menu, View menu and keyboard shortcuts.
Cut: Remove the selected audio data and places it on the clipboard.
Only one "thing" can be on the clipboard at a time, but it may contain multiple tracks.
Copy: Copy the selected audio data to the clipboard without removing it from the project.
Paste: Insert whatever is on the clipboard at the position of the
selection cursor, replacing whatever audio data is currently selected, if any.
Trim: Delete everything but the selection.
Silence: Erase the audio data currently selected, replacing it with silence instead of removing it completely.
Undo: Undo the last editing operation you performed to your project. Audacity supports unlimited undo - you can undo every editing operation back to the last time the document was closed and re-opened.
Redo: Redo any editing operations that were just undone. After you perform a new editing operation, including resizing a track, you can no longer redo the operations that were undone.