That is because there are many quadratic functions that have the same axis of symmetry. If a function is multiplied by a constant factor the axis of symmetry remains the same but the curved part of the graph widens or narrows.
For example x^2 + x - 6 and 2x^2 + 2x - 12 The last function will have same axis of symmetry and same roots as the first but the curved part will be narrower.
Also if we multiply the first function by -1 the curve will flip about the x axis but will have the same axis of symmetry
