To keep a form size manageable I allow the scrolling text option. However, when the form is submitted and approved with a digital signature I lock the fields as read-only (what use is a signed form that can be altered?). However, setting a field as read-only disables the scroll function, so the full content cannot actually be read any more.
In the absence of any other obvious place to grumble about this design, I'll do it here!
But here's what I do in Acrobat:
I create a text box that I estimate/or decide that should be big enough for a reasonable answer.
Then, I set the properties to Multi-line, but not scrolling. Works perfectly.
Most people are not going to write that much, anyway.
Hope that helps...
Acrobat is probably the program I use most often and I'm learning more every day.