How do you change your age on

I have gone to preferences but it doesn't show anyway or option to change it, It currently says I'm 14 but I'm younger and in high school. I originally put 13 but the birthday I put in hasn't passed so it shouldn't have automatically changed.

Ab c d e f g h i j k l m n o p

Cprogram to find //perimeter of rectangle printf(" \n perimeter of rectangle \n"); printf(""); printf("\n enter width and length of the rectangle : "); scanf("%f%f", & width,& length); perimeter = 2 * (width + length); printf("perimeter of rectangle is: %.3f", perimeter);