What cause the steering column to randomnly reset to the down position?

Owner, Read your Owner's manual, get well versed on the operation of your Driver Memory Settings, and make sure that you are using the key for your preferences, If you have a different key, ( spouse ), the system will read those settings, Once that is verified, if you still have the same issue(s), then there may be a problem with the module which controls your steering column settings, the repair / replacement of which would probably require a visit to the dealer, or a BMW specialist who has invested in the Scan Tool Required to interface with your vehicle.