what do FiniteDiff​erenceStep​Size,Diffm​inchange and Diffmaxchange do ?

In my optimization problem my obj function is

function OBJ = Obj(X)

OBJ = X(:,11);

end

and my NonLinCon function is

function [C, CEQ] = NonLinCon(X, NCHV, PCHV, IN_SPEC)

DOF.M(1).L = X(:,1);

DOF.M(2).L = X(:,2);

DOF.M(3).L = X(:,3);

DOF.M(4).L = X(:,4);

DOF.M(5).L = X(:,5);

DOF.M(1).RHO = X(:,6);

DOF.M(2).RHO = X(:,7);

DOF.M(3).RHO = X(:,8);

DOF.M(4).RHO = X(:,9);

DOF.M(5).RHO = X(:,10);

DOF.IB = X(:,11)*1e-3;

[~, OUT_SPEC] = aaSynFoldedPmosOL(NCHV,PCHV,DOF);

C(:,1) = IN_SPEC.UGF ./ double(OUT_SPEC.UGF) - 1;

C(:,2) = IN_SPEC.PM ./ double(OUT_SPEC.PM) - 1;

C(:,3) = log10(IN_SPEC.AVDC) ./ log10(double(OUT_SPEC.AVDC)) - 1;

C(:,4) = IN_SPEC.FO ./ double(OUT_SPEC.FO) - 1;

C(:,5) = IN_SPEC.FP1 ./ double(OUT_SPEC.FP1) - 1;

C(:,6) = IN_SPEC.VO_SWING ./ double(OUT_SPEC.VO_SWING) - 1;

CEQ =[]

where in_spec are given by user

when i try to run fmincon on my problem with a feasible starting point it give me a local minimum without using any options but when i use FiniteDifferenceStepSize set to 1e-3 or Diffminchange set to 1e-3 or Diffmaxchange set to 1 it gives me the same point every run and that point's is better than my local point and even better than the point found when i use genetic algorithm in vectorized mode so my question are

1- what do FiniteDifferenceStepSize, Diffminchange and Diffmaxchange do ?

2-what are other vectorized global solvers that do not use random generations of starting points ?