Hi there.
If I understood your English well, you' re asking for the RIGHT MIRROR, NOT TILTING DOWN when on reverse, yes?

If the switch that controls the mirrors (Left-Right) is turned to the RIGHT, on REVERSE the RIGHT mirror WILL NOT TILT.
If the switch that controls the mirrors is turned to the LEFT, on REVERSE the RIGHT mirror WILL TILT down.

If you used the SEARCH feature, you could have found this info...