Currently, under Win10 & JMP 14.3 Pro, it appears that the only way to reorder independent variable terms within the Construct Model Effects box in the Fit Model dialog is to remove them, then re-add them in the desired order. I would like to suggest allowing their order to be shifted up/down simply by clicking and dragging within the box. This would be especially helpful for fitting models using Type I SS (where predictor effects depend on the order in which they are entered into the model).