It may take some time to have your new positions hold.
I recommend doing mobility sessions 2 or 3 times a day. It doesn’t have to be for a long time, but the muscles tissue need the positioning reset in the beginning. You are undoing a habit of another position and like breaking any habit it takes reminders on the changed positioning. Keep sessions to a max of 2-3 mobs per session.10-15 minutes. A minimum of 2:00 per mob. 2:00 is the minimum dose.
Do you have differences left and right side? hamstring/hip capsule, ankle tightness?
Squeeze your butt to set your pelvic position
Episode 128: The Pelvic Fault and Back Pain
Psoas
Jill Miller Smashes Your Guts! (and psoas, and tacked down viscera, and matted down abdominals…) Part 2
Episode 301: Psoas Flossing and Biker Hips
Episode 75: Your Inside Psoas Bits, World Record?
Episode 40: USAW Oly Prep: Some New Hip Love /Psoas/Calves
Episode 26: Hips and Seppuku: Psoas and Hip Soft Tissue Mob
QL
The QL Is NOT a Bone…Even in THE Matt Chan
Pro Episode #4 – Spinal Fault/Tweak
Hip Flexor
Episode 142: Tight IT Band and Hip Flexor Fix: Runners?
Episdoe 23: Runner’s Legs
Episode 144: Ze Hip Flexion
Episode 04: Silent P in Filet, Very Paleo
Episode 347: Stiffness Kills– New Anterior Hip Flossing Tweaks

Jill Miller has some great low back quick fixes here
A link for a free quick fix is here you can purchase others for a small fee.
Low back pain can come from a few sources. What is your sleeping position? Overextended?
Episode 39: Sleep, Pillows, and What Your Low Back Says About Your KB Swing
Episode 42: Creative Pain, Low Back Decompression, Hammies