On all drum brakes with self adjusters the star wheel edge toward you - toward the center of the vehicle - goes upward to tighten. That's IF the star wheels haven't been switched side for side.
To loosen you have to push the lever off the star on the outside - use a thin screwdriver through the hole while turning the wheel down to push it back.
Be sure the parking brake cable is very slack when you adjust them.
With it being a bias problem, it probably has "lifetime" linings on it. They are way too hard to stop correctly. Aftermarket brake mfgrs have forgotten that brakes are friction devices.
Replace with with cheapies - they are much softer than the super hard lifetime junk. They stop! The parts guy will tell you they don't last long, Bull!
And they stop like it should.
Daanb - squeel - same problem, hard linings (linings on the shoes for drum brakes, pads for disc brakes.)