Guest cannot post if a forum is set so that 'only members can post', if you have your forum set to that, and have guest posting, please let us know so we can investigate.
The preservation of member's posts is to give members more rights on Lefora then they other forums. Admins cannot change posts as to preserve the speech of members. You could consider this more of a philosophic choice of the Lefora team and can read more about it here - http://support.lefora.com/2008/10/08/frequently-asked-questions-w-answers/page1/#post1312551 We have plans to build out more features here around allowing updates by admins on existing member posts (clearly marked).
We're sorry that transition to this fact may be abrupt if your forum behaved another way in the past. There are a number of features on Lefora that don't exist on most other forum software, like the ability to embed youtube videos, automatic spam detection, rich user profiles, a rich text editor, and search engine optimization on public forums.
If you are having other problems with your forum, we can investigate, just email me directly at 'chief -at- lefora.com' with a link to your forum and a description of your problem. If you have other feedback and criticism, I'm happy to hear it as it gives us a better understanding of what features to build out on Lefora - we're in active development, adding new features weekly (another thing you probably haven't seen on other forum software). We're working hard to make the transition of takeforum forums a smooth one, and are fixing any problems as we're made aware of them.
Find me answering questions on support.lefora.com or howto.lefora.com