Two problems with new forum

I started a new forum with Bizhat, and I have two problems.

One, I cannot change the avatar size permission beyond 6,144 bytes, which is ridiculously small. It simply will not accept larger numbers.

Two, I cannot set the forum permissions, it just takes me back to an admin page where it gets "stuck" on that page. I want to set it so that only registered members can post.

Any advice?

Make sure that size of your avatar is 80x80 ok?
Second question! I dont know why you are having that problem since by default nonregistered users are not allowed to post!