Depress the button on the seat belt buckle. If the belt does not fully retract, pull it out and check for kinks or twists. Then make sure it remains untwisted as it retracts.

NOTE
If a belt does not fully retract, inspect it for kinks and twists. If it is still not retracting properly, have it inspected at an Authorized Mazda Dealer.
Fastening the Seat Belt
Front Shoulder Belt AdjusterMazda 6 Owners Manual: Rear seat disassembly/assembly
4SD
1. Disassemble in the order indicated in the table.
2. Assemble in the reverse order of disassembly.
5HB
1. Disassemble in the order indicated in the table.
2. Assemble in the reverse order of disassembly.
...
Mazda 6 Owners Manual: Luggage Compartment
Loading golf bags
Golf bags can be carried in the luggage compartment.
Up to three golf bags can be carried in the luggage compartment.
Place each of the three golf bags into the luggage compartment with the bottom
of each bag pointed to the left, and then set the top of each bag so that it is ...