Both of these sitting postures are poor.
It is rarely the accident or the unusual lift that causes problems but your daily grind or habits that are the cause.
If you watch most 5 year olds they bend and squat like olympic weightlifters; they have perfect form. As soon as we force our children to sit for long enough they start to loose those natural movement patterns and bend, lift and sit abnormally (like most adults).
It's better to be inspired by great posture, great health, feeling well than to wait until you are desperate for help to correct an established problem caused by an established habit.
Try to lead by example and inspire others to choose different daily habits. Come to see your Chiropractor for inspiration, not through desperation.
Inspiring Posture