Just to come back to the original post, the autopilot must have a course reference, consider that if you are positioned left of the runway the needles will indicate fly right whatever your heading (ie even if flying away from the runway. The course bar is used in the autopilot as a reference, if you are flying with a crosswind then there will be a permanent 'course error' equating to your track angle - this error is washed out and ignored after a set period of time, however if the course bar is moved then the error signal is reinjected. Some very old systems may not reintroduce this signal and this could be what you are seeing, but essentially once the qdm is set the course arrow should not be moved (not sure why you would want to anyway).

regards

Jase