On snatches, as the bar passes the knees and you begin thinking of the final explosion, you need to stay flat footed as long as possible and use the lats and posture to bring the bar back toward your hips rather than reaching the hips for the bar (yes the hips will move forward toward the bar, but let that happen naturally). Reach a finish extended position in which the shoulders are a little behind the hips - you're pretty close to vertical.
In the clean, you have a similar issue, but it may be coming more from trying to push your knees too far back too soon, so you end up having to shift forward in compensation. Keep your chest up and just shift your weight to your heels as you leave the ground without focusing on pushing the knees back specifically. Then same as sn, stay flat footed as long as you can and think of pushing the bar back into your lap rather than reaching for it with your hips.
The jerk problem is simple - your step isn't short so much as you're diving your body forward. Immediately as you dip and especially as you start driving up, you're entire body is shifting forward. You need to dip and drive vertically. Imagine a vertical line through your ankle, hip and center of the bar, and keep those 3 points in that line throughout the entire dip and drive. Only after you've finished driving straight up do you split the feet. Don't reach your chest through the bar so much - imagine bringing the bar back behind your head and reaching through with your front heel and hips instead.