Colour Mask 10.4

Could someone help me with this new colour mask feature on FCPX 10.4 as I have muliple areas I would like to
change the colour but when I add a colour mask say to the sky to change its colour, it doesnt seem very clear to me how to change another area of the shot like enhance the green grass area of the shot. It only seems to allow one colour mask unlike previous versions of FCPX. Can anyone help as Im sure the feature is available but I just cant crack this. I have looked at you tube etc but most videos seem to be the old version.

Many thanks

You never could apply TWO or MORE color masks in the same instance of corrections. You'd have to add a new correction. All 10.4 color tools have color masks and shape masks, and for clean secondary corrections, you'd usually use them additionally. Watch here, and start at 7'30":


Some really helpful tricks there. Ever since Color Correction became an effect in FCP X, you have to stay aware of the order of corrections. Like when you affected the sky and afterwards wanted to change the grass, you'd do that on top of the first correction (that means; down on the list). That's why it's so crucial to make a very precise selection. A spatial mask ("power window") excludes everything outside, with feathered borders, a color mask is the only way to *feather* an HSL selection, the combination of both is the best option for such a task. Note, how "add, intersect, subtract" appear as pop down choices if you combine them.