Hello from vancouver
well the rise is the rise, it is the total rise divided by your number of risers. The only way to change this (without changing your stair layout/flooring) is to change your number of risers. Remember you have to keep it to within code.
your run can be whatever you want it to be,within code, providing you have the room for the staircase with a certain run.
what you do when building stairs is follow a stair proportioning rule, to keep your rise/run in proportion. Deeper treads typically should have shorter risers.
I would rebuild your stairs completely to follow code.
rise plus run equals 17 to 18 inches
rise times run equals 70 to 75