Each time you start Adobe Audition, it keeps track of the edits you perform. Edits aren’t permanently applied until you save and close a file, giving you unlimited undo and redo capability.
Undo or redo changes
To undo a change, choose Edit > Undo [name of change].
To redo a change, choose Edit > Redo [name of change].
To repeat the last command in the Waveform Editor, choose Edit > Repeat Last Command. You can repeat most commands; however, there are a few exceptions (such as Delete).
To repeat the last command without opening its dialog box, press Ctrl+R (Windows) or Command+R (Mac OS).
Compare history states
While the Undo and Redo commands restrict you to an incremental sequence of changes, the History panel lets you instantly revert back to any previous change. Use the panel to quickly compare processed and original audio or discard a series of changes that produced undesired results.
History states disappear when you close a file.
To revert to any history state, click it.
To incrementally move through states, press the up and down arrows on the keyboard.
When you work with very large audio files, delete unnecessary history states to clear disk space and improve performance.
To delete all states, choose Clear History from the panel menu .
To delete a specific state, select it, and then click the trash icon .
Deleting history states also removes related Undo commands.