Subaru 2004 Impreza Owner's Manual page 51

Seat, seatbelt and SRS airbags
4. Insert the center seatbelt tongue plate in the center
seatbelt buckle marked "CENTER" on the left-hand
side until it clicks.
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5
6
5. To make the lap part tight, pull up on the shoulder
belt.
6. Place the lap belt as low as possible on your hips,
not on your waist.