Are you doing a stockinette stitch? If so are you adding the colour on a knit row? If you add it on a purl row, it will show on the RS. Try adding your next colour on a knit row. The only place it will show then is on the WS. Good luck!
I love to give homemade gifts... which one of my kids do you want?
Find our "Canadian Oddball Blanket KAL" on Ravelry as: OddballBlankets