The car seat base isn’t secure. Ensure when you initially install the car seat that you thrust down with all your weight to ensure the base is secure and snug in your backseat. The fix? Loosen up the seatbelt to reset the base into the backseat and tighten the seatbelt https://garrettniypu.blogzet.com/about-the-best-booster-car-seats-47671308