This is what it says in my instruction manual (I got one the other day)

To alternate to the opposite breast, you will need to change over the inner and outer straps. When you have finished feeding your baby on one side, take your baby out of the carrier. Pull the fabric of the inner strap out through the rings and take over the top of the opposite strap. Re-thread in the same rings. You can now put your baby back into the nursing position, this time on the opposite side.

Hope that makes sense?