Edit the field order and placement on Custom Forms and Service Items

We want to dress up our forms and also try to mimic some of our old forms we are replacing to make things easier for our end users.  While its great that these have some default fields, I need to be able to put them in different orders and placement.  I get that I can control that on the custom fields based on the order they are entered.  But I need to be able move some of the default fields around.