I just asked a question and gave some personal information. I hope that is kept confidential and is erased when finished.
We understand your concern about private information on this forum. If you can see the little gear in the upper right corner of the original post you may click on the gear and then edit your post.
Otherwise when someone contacts you by clicking on your name and then Message that communication is private between you and that person. Our missionaries will use that mode to request private information. Please note that that missionary will have Mod next to their name in the public forum thereby identifying them as being official.
Hope this allays your fears.