Note that positive shifts can lead to the audio being truncated at the right edge when shifting a stereo track. To avoid this, split the stereo track using the Track Drop-down Menu, select each track in turn and apply the shift you want using the Mono/left channel shift field. If the audio starts after time zero and is preceded by empty space, convert the empty space to silence with Project > Quick Mix in legacy Audacity up to and including version . In current Audacity , select the track, press J , then press SHIFT + HOME , then Generate > Silence . This prevents truncation of the audio providing there is sufficient silence at the start of the track.