The old Project will have whatever Color Pallet was the default when the Project was created.
Use “Reset Color Set to Default” in the Project to have it use the new default colors. This may cause some of your existing colors to change. I believe that Cubase uses the colors based on the position in the color list. So in your example the red Color 1 tracks will stay the same but Tracks colored orange Color 2 will now be the maroon of the Untitled Color. Because of this it is best to add new colors onto the end of the list so it doesn’t cause the other colors to shift their position in the list.
Hey Raino thanks I tried this now, you’re right about inserting new colors it didn’t work well but when I just edit an existing color and save then I can reuse it
Thanks!