Question here hun, are you taking the working yarn BETWEEN the needles each time you have to change from a knit to a purl or vice versa? When you knit a stitch, the yarn needs to be back of the needles. When purling, the yarn needs to be in front.
To change which side the working yarn (the yarn from the ball) is on, you bring the yarn BETWEEN the needles, not OVER. So like this… k, k, k, bring yarn between the needles to the front, p, take yarn back between the needles to the back, k, k, k,. etc.
Hope that helps ya hun.