In DaVinci Resolve 14, some operations can be performed on all of the Y, R, G, B channels at the same time or only on one of them.
What is the difference between adjusting only Y, or adjusting all of YRGB? The effect looks the same.
My statement that the effect looks the same was incorrect. The use of these sliders is explained in the manual, in "Primary Grading Controls" -> "Color Wheels Palette" -> "RGB Lift/Gamma/Gain Sliders" (page 725 in the v14 manual). Quoting:
... These three controls allow easy Y-only adjustments to contrast, where an increase in contrast results in perceptually diminished color saturation.
Making Y-only adjustments to contrast is a great way to increase contrast when you’re going for muted saturation or a gritty look. This kind of adjustment is also useful in situations where you’re trying to increase shadow density without increasing image colorfulness.