The Rotate Colors feature changes the position of every checked color all at once. It is most useful when you have already reduced the colors to a small number of colors that are obviously different from each other.
When colors are rotated, the second checked color becomes first; the third checked color becomes second; and so on. The first checked color moves to the end. Only the checked colors move; unchecked colors are ignored when the colors are rotated.
For example, suppose you have a fabric with three colors checked:
Clicking the Rotate Colors button at this point moves all three of the checked colors. The second checked color (in this case, Blanca Peak) moves to the first position, the third checked color (Sap Green) moves to the second position, and the first checked color (Sky Watch) moves to the bottom.
The fabric image refects the same color changes. So, for example, the background becomes Blanca Peak instead of Sky Watch. Custom Search would now try to find fabrics where Blanca Peak is more dominant than Sky Watch.
Clicking Rotate Colors again has a similar effect.
This time, Sap Green becomes the background color.
Clicking Rotate Colors one more time puts Sky Watch back at the top, in its original position.
The fabric is back in the state it was in before we started rotating colors.
Remember that the color at the top of the list is the one that appears most frequently in the fabric, and the color at the bottom of the list appears least frequently. Rotating the colors is a good way to change the relative priority of the colors in the Custom Search.