Microsoft Office 2007.. Issues with word

First of all I hope this is the right place to post and apologies if it is not.
Second of all I feel a bit silly having to ask this question but it has been bugging the hell out of me.

I'm completeing an interview pack for my nursing interview and I need to complete 5 different sections. This is all in Microsoft word 2007.
A blank box is inserted in the page and that needs to be filled.
However every time I type in the box, the box expands. There is a strict instruction at the end of the page stating expanding the box is forbidden. I know I can just decrease the box myself but now each box is a slightly different in size. And I don't want to present the completed version without it being completely correct.

I just need to know if there is a way I can ensure the box doesn't expland as I type.
I've tried office help and searched online, but I only seem to be able to make the whole document read only.
Thanks in advance guys;)