BT, there is a time limit on which you can go back and edit your post. I think the setting is set to 30 to 45 minutes from the time you submit the post. The time limit is intended to prevent the unhappy user from going back and disrupting the board by editing or deleting all of his posts etc. Moderators will find they are not affected by this time limit.
“Only when you drink from the river of silence shall you indeed sing. And when you have reached the mountain top, then you shall begin to climb. And when the earth shall claim your limbs, then shall you truly dance.” ~ Kahlil Gibran