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 AdjusterVariable Valve Timing Actuator Removal/Installation [Mzr 2.3 Disi Turbo]
WARNING:
Fuel vapor is hazardous. It can very easily ignite, causing serious injury
and damage. Always keep sparks and flames away from fuel.
Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious
injuries or death and damage. Fuel can also irritate skin ...
Liftgate Adjustment
1. Measure the gap and height difference between the liftgate and the body.
2. Loosen the liftgate hinge installation bolts and adjust the gap by moving
the liftgate.
Standard clearance
a: 5.0―7.0 mm {0.20―0.27 in}
b: -2.0―0 mm {-0.078―0 in}
...
Scheduled Maintenance (U.S.A., Canada, and Puerto Rico)
Follow Schedule 1 if the vehicle is operated mainly where none of the
following conditions
(severe driving conditions)apply.
Repeated short-distance driving
Driving in dusty conditions
Driving with extended use of brakes
Driving in areas where salt or other corrosive materials are used
...