When you go into your sketchbook you will see the block without color. just look below it to find the arrows. all you have to do is click on the right arrow to see the next color version of that block. The sketchbook stores up to 10 versions of a block in one place. You will see the block without color and then you click to see the next one and you will see the first color combo you saved. When you change colors in your quilt or block on the worktable the sketchbook will save every change you make. so when you go into sketchbook to see your block or quilt you will find several color versions of that same block in one place. you just have to click the right arrow to see the next one in the "pile" of blocks. as if you had stacked several blocks on top of each other. hope that makes sense.
As for the saving you dont' have to do both one or the other will save it. It is quicker to just click on the sketchbook pic that saves it than to go to the menu and find save.