eyoung - When you first open the HTML Editor behaviour on your UPDATE page, you will see the initial value there but when you save it, it will disappear. Like many option boxes in the WA tools you need to set the option, then click into another field, prior to clicking OK, SAVE or NEXT, otherwise, your change disappears.
I am having a similar problem with the uploads though. I have enabled File Management and set up Security Assist but it is still not working.
Q1. do I have to do this for EVERY HTML Editor behaviour on each page?
Q2. after I make the changes to an Update page, specifying File Management, folder info and Global settings, what files do I need to upload?