Question

How much potential energy does the ball have when it reaches the top of its ascent

Answer 1

Its has the most it will have during its descent because as it goes down the kinetic energy replaces potential

Answer 2

At the top of its ascent, the ball has  potential energy equal to

            (its weight) times (the height of its ascent) .

If we knew either of those quantities, then we could give you
a number for its potential energy.  But the question has no
given information.