Thanks a lot for the answer. Sure, you are right, color choices are personal choices. But it was just a little statement and i thought may be someone would have an idea for another color and propose it. I will exercise the way to unmerge, i saw the function “Promote selection to a layer” but had not the idea to try it because no association in my head and didn’t take the time to look what it means.
I proposed another sandwich in the showroom, both pictures were placed in the wrong way after “submit”. I was not able to change it and saw afterwards why they were inverted (?).