Don’t listen to solutions from playtesters
The solutions offered by playtesters may work, but probably won’t solve your problems effectively. Try to listen to the problems that lie underneath.
In early prototypes of Circles people often suggested I set circle colors based on their behavior. But this ran counter against the exploration and discovery elements the game was about. But clearly there was a problem. Players had a hard time discovering the function of circles and got confused when they were mixed up. Instead of changing the visuals, it became much more effective to make changes in level order and level designs. Now new circle types are introduced in a steady pace and always start with a new color palette. When mixing them up, circles are often bigger to illustrate their behavior better. I haven’t heard the suggestion ever since. Success!