How to set the legend

[Pierre-Moulin]

I have some issues with the color map :s
-Why the legends are adding themselves
-How to come back to the default one ?
-I would like to set a gradient 70 (green) -->80 (red) dB with an isobar at 75 ... what should I do ?
Thanks for your help :)

[cmarchetto7]

Choosing the color scale, quitting and re-opening the project seems to work with me (surely a bug).
Hope it helps