Sorry it took so long to reply but I must have missed this the first time around. You didn't say if you created the forms or are using forms someone else made. Assuming they are someone else's forms, what probably happened is that when they created them, they selected autofit for the font size. So unless the type-in box they created for each item is exactly the same size height wise, the fonts will shrink of enlarge to fit the box. If you have the full Adobe package, then you can edit the form and selected a specific font size so that they are all the same. IF you don't, I think you are out of luck. I don't know of any programs other than Adobe that will edit the form settings.
John