STEERING WHEEL TURNS BY ITSELF. REPLACED VALVE ON BOTTOM OF CAR

Steering valve not set to neutral.

If it pulls to one side; a wheel alignment is needed regardless of the steering wheel.

the problem may be that there is a faulty control valve in the power steering part of the steering and it is allowing pump pressure past and turning the wheel. Best have a pressure test done before you spend big bucks as it may be the control valve body that needs replacement.

How was it working before you replaced the parts ?
Normally the front alignment makes the car want to return to center.

I'm going to agree with the rack conclusion. Keep in mind I can't see it for myself.
If you take the load off the front wheels, you should be able to turn the steering wheel without effort.
If the effort changes while turning the wheel, the only things affected would be the rack and the column.
If you notice it turns ok with the engine off but not with the engine running, it could be something with the pump or one of the lines, or still something with the rack.

It is either going to be the power steering pump or the steering rack itself.

Take it to a technician and let him do the tracktion control rod check and a four wheel laser tracking.

your front end needs to be checked for worn parts,,,,fixed and then have an alignment done

Sounds like a malfunctioning valve in the system...sometimes replacing the fluid (do at least twice to get it all out) will help but many times it requires rack replacement. If you want to attempt fluid change just remove low pressure hose and drain (low one does not have pressure fitting, just a clamp) Re-fill and run, then do it again. If problem does not change within a few hours of driving, likely it will not.

The Active Steering system uses a Papst brushless dc motor to rotate the cage (ring gear) containing the planet gears a planetary gearbox at the bottom of the steering column. The motor effectively changes the steering ratio by increasing or decreasing the amount of gearbox output rotation relative to changes in the steering-wheel angle input. The resulting ratio depends on the speed of the car. For instance, a low 10:1 ratio gives high maneuverability for parking in tight spaces, with less than two turns of the steering wheel, lock to lock. To track straight at highway speeds, where even a small steering input can produce a quick sideways acceleration, the electric drive boosts the ratio to 20:1. Cars without Active Steering typically have ratios halfway between (specifically 14.1:1 for the BMW).
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Now, if your active steering does not work , the car reverses back to power steering and the ratio is 15.1:1 so the car can be driven but the "active steering " is not working and still needs to be fixed.
It the unit needs to be replaced and your car is not under warranty, the repair cost may reach 5000 dollars.