Adjust the rear-view mirror by hand until you can comfortably see out the back window without moving your head. You’ve got the right position when the mirror frames all four corners of the back window, and you can see the edge of your head restraint in the lower right-hand corner.
Avoid putting fingerprints on the mirror surface; hold the mirror by its edges when you adjust it.
Use your car’s manual or electric controls to adjust the left and right side-view mirrors. Aim to get the line of the horizon about halfway down the mirror. Sky, trees, and houses should be in the upper half of the image; the road, pavements, and nearby fields should be in the lower half.
Adjust also so that the side of the car is just visible on the extreme left-hand edge of the right mirror and on the extreme right-hand edge of the left mirror.
Keep adjusting the mirrors until you can see their images comfortably without straining your head or neck.