Select Menu: Tracks
From Audacity Development Manual
These commands extend the current selection up and/or down into all tracks, or Sync-Locked tracks in the project.
In All Tracks Ctrl + Shift + K
Extends the current selection up and/or down into all tracks in the project.
- Before extending the selection - with selection in just one track
- After extending - the selection now extends across all tracks
In All Sync-Locked Tracks Ctrl + Shift + Y
Extends the current selection up and/or down into all Sync-Locked tracks in the currently selected track group.
- Before extending the selection - with selection in just one track and with a Sync-Locked track
- After extending - the selection now covers the original track plus the Sync-Locked track