how to assign the minimum and initial increment size?

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Hi all, I am facing many problems with this module can any one please tell me how to assign the initial and minimum size increments is it depends on the load or things like meshing, geometry, contacts or the boundary conditions.
I have tried reducing and increasing the step values but it did't even work for simple models like a bolted lap joints.
can any one help me out to sort this problem?
thanks guys in advance..