To undo the last change made to a soundfile or a detection file (introduced by choosing items from the Edit or Toolbox menu), use the Undo last edit command from the Edit menu. The size of the undo buffer can be modified using the Preferences dialog available from the Options menu. If you accept the default ‘unlimited’ buffer size setting, all changes introduced during the last editing operation will be reversible (provided there is enough free space on your computer). Since working with very large buffers may slow down editing and create some memory problems, you may limit the size of the undo buffer. In cases like that we suggest you secure long audio files by using the Create undo file command from the File menu.