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 AdjusterTiming Chain Removal/Installation [Skyactiv G 2.0]
WARNING:
A hot engine can cause severe burns. Turn off the engine and wait until it
is cool before servicing.
CAUTION:
If the camshaft is rotated with the timing chain removed and the piston at
the top dead center position, the valve may contact the piston and the engine ...
Oil Cooler Removal/Installation [Mzr 2.0, Mzr 2.5]
WARNING:
Hot engines and engine oil can cause severe burns. Turn off the engine and
wait until it and the engine oil have cooled.
A vehicle that is lifted but not securely supported on safety stands is dangerous.
It can slip or fall, causing death or serious injury. Never work ...
Front Seat Slide Adjuster Removal/Installation
WARNING:
Handling the front seats improperly can accidentally deploy the side air
bag, which may seriously injure you. Read air bag system service warnings and
cautions before handling the front seats..
CAUTION:
After removing a front seat, do not operate the slider leve ...