Lincoln 2013 MKX Owner's Manual page 23

Child Safety 23
Children and booster seats vary in size and shape. Choose a booster that
keeps the lap belt low and snug across the hips, never up across the
stomach, and lets you adjust the shoulder belt to cross the chest and
rest snugly near the center of the shoulder. The following drawings
compare the ideal fit (center) to a shoulder belt uncomfortably close to
the neck and a shoulder belt that could slip off the shoulder. The
drawings also show how the lap belt should be low and snug across the
child's hips.
If the booster seat slides on the vehicle seat, placing a rubberized mesh
sold as shelf or carpet liner under the booster seat may improve this
condition. Do not introduce any item thicker than this under the booster
seat. Check with the booster seat manufacturer's instructions.
2013 MKX (mkx)
Owners Guide gf, 2nd Printing
USA (fus)