Question

how does changing the shape of mirror affect the shape and position of an image??

Answer 1

This can be understood by the fact that the size of the image is its magnification of the original image m = -v / u

so if the position changes the size will change .
As the shape of the mirror shows its focal length (or radius of curvature)and changing the focal length will change the position of the image and hence changing the magnification .