Hi Ive been watching a few videos to help learn sonar and I noticed on the tracks on the video, there is a yellow coloured block are the very left of each track and on the tracks where there isnt this colour there is a blank space/cel for the colour to go. Cant figure out what the colour means or why it is there. Any help would be great, I know its only a small thing but its driving me crazy.

From the manual, page 1232 :

The WAI display

The WAI display (short for Where Am I) is a group of colored markers to show you which tracks and
or buses are currently being controlled by which controller/surface. Each controller/surface uses
different colored markers.

In the following picture controller/surface 1 (blue markers) is controlling tracks 2-5, and controller
surface 2 (red markers) is controlling tracks 7-14. You can drag the markers to different groups of
tracks to change which tracks each controller/surface is controlling. You can also double-click the
WAI markers to open the property page of that particular controller/surface.

It's possible that the person in the video is using a control surface.
 
I use a Cakewalk A-300 PRO as a control surface, and the left hand side of the tracks (and bottom of the Console View) are orange to show which bank of eight tracks are currently controlled by the A-300.

That explains it, Im not using a controller so no lights. Thank you both :)