Sure you can, but you have to actually edit the file. For instance, in the faq page, you will find this code for the textarea:
PHP Code:
print_textarea_row($vbphrase['text'], 'deftext', $faqphrase["$defaultlang"]['text'], 10, '70" style="width:100%');
If you look at the function print_textarea_row (in adminfunctions.php), you will see that the 10 is the number of rows and the 70 is the number of columns. So, you can change the 70 to something larger, like 150 or so.