How do I properly position the shoulder belt when using the car seat as a booster?

In both high-back and backless booster modes, the shoulder belt MUST cross midway between the child's shoulder and neck. In high-back booster mode, thread the shoulder belt through the shoulder belt guide so it is even with or just above the shoulders. If using backless booster mode and the shoulder belt does not naturally cross midway between the child's shoulder and neck, you should use the shoulder belt clip to adjust it. The shoulder belt MUST NOT cross the child's neck or fall off the child's shoulder. (Pages 55, 59, 61)