plot function in GA toolbox (change the sign of fitness value)

Hi every body

in GA optimazation toolbox I want to maxzmiztion my objective function so i minimize the negative of the function

in data entry box labeled Fitness function i have entered

@(x)-mohfun(x)

my problem is in plot function when i chose best fitness as shwon in photo fitness value is negative

can i make it positve whith the same result