I have the same problem with driver's side mirror. I have to hold it when I open the car or let the car stand without looking it. I fixed it before by doing the same re positioning that everybody talk about and it worked for some time. However, it stated doing the same thing again and unfortunately the re positioning fix does not work anymore.
I suspect that there is a stopping pin that should stop the mirror in proper position. I think that pin was broken and this mechanism should be replaced.
Will post pictures if prove my theory or find a solution.
Question: Is there an easier way to disable the folding mirror option rather than the one mentioned above with coding procedure? I tried to remove (there are two fuses for mirrors) fuses and it disables my windows as well.