if i remember correctly there is a way to change it in some forums but i doubt it's in the mod permissions. would have to be in the administrator area. and there's a bunch of stupid settings in the something or other script that controls how php responds as well but is a pain to find depending on your host. My actually be in there. called a php.ini file or something...

best is as mentioned. type long posts in a text editor and then copy or paste. I always copy text to to my clipboard before posting just in case it doesn't pull back up with the back bottom.