I find if I wear my smart carry barely tight enough, I can get it to hang low while standing, but still allow it to slide up when sitting down.
Sometimes when i sit, the muzzle is poking out of my jeans. If I loosen the velcro a little bit, the fabric of my jeans strong enough to prevent my muzzle from printing... that is if I wear the smartcarry loose enough to let it adjust itself. Then, when I stand up, the weight of my firearm pulls the pouch down low where it should be.
Just give it time. I've had mine for a couple weeks and I am still finding out new things about the holster.