Adding more lines to a block field: fillable form only allows one line?

I am trying to fill out a form with blocks of text that I need to add; however, I seem to only be allowed to add one line of text at the center of each blocked-in field, and the 'enter' key does not allow me to move down to another line in the same field. The text just runs out of the view of the field. Is there a way to make adjustments to the field to add more lines? I am not the creator of the document and I am afraid some ways to fix this may have been disabled. Using the "fill and sign" function does not seem to give me any more options to change this. Is there a way to solve this problem within basic Acrobat Reader?