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 AdjusterBrake Fluid Pressure Sensor Inspection
1. Switch the ignition to off.
2. Install the SSTs to the master cylinder (secondary side) as shown in
the figure.
NOTE:
When installing the SST (49 D043 0A0) to the master cylinder, use
a commercially available flare nut wrench (flare nut across flat 12 mm {0.47
in}).
...
Child-Restraint Precautions
Mazda strongly urges the use of child-restraint systems for children small
enough to use
them.
You are required by law to use a child-restraint system for children in the U.S.
and Canada.
Check your local and state or provincial laws for specific requirements
regarding the safety
of ch ...
Parking Support Brake function (static objects front and rear of the vehicle/static
objects around the vehicle)
Within the Subaru Solterra, the Parking Support Brake system continuously
monitors the driving path for stationary obstacles such as walls or fixed structures.
If the sensors detect a static object and the system determines that a collision
could occur — for example due to unintended acceler ...