Tracks inseparable

OS 10.12.6 Audacity version 2.1.3
This problem started with the appearance of little clock faces all over a track. If I have two tracks I can’t move them separately using the double arrow even if only one track is selected. happens with aligning tracks also e.g. to the start. Screen shot attached.
Audacity screen.jpeg

You have accidentally enabled “Sync-Lock”.
Turn it off by clicking the “Clock” button.

The current version of Audacity is 2.3.1 and is available via the Audacity website:
In the current version, that button has been removed, and Sync-Lock is now a menu item only (“Tracks” menu), so is less easy to accidentally enable.

There is no button anymore - we removed it a while back to prevent accidental triggering.

Sync-Lock Tracks can be turned on or off at Tracks > Sync-Lock Tracks.