@kgerrow Thank you for the quick reply.
The feature service is created, then I usually just open the service in a map by clicking on the service itself. Then I'll just simply save the map and work on it from there. This layer is only meant for this map. So whether its map settings or feature class settings doesn't matter although I've tried both.
The feature class Data tab is where I was trying to update the hidden fields to not be hidden but the check boxes weren't sticking. I also tried changing the settings from within the map in the feature class table but that didn't work either.
In the Visualization tab, the hidden fields do not show up when trying to configure the popup unless I go to Configure Attributes as shown below. Then the attributes will show up in the list for the popup and there is an option to check the fields to be shown in the popup. When I check the fields for the popup they seem to remain visible in the attribute table as well. This is not right and this should not be the method to make these columns visible.
I really feel like I shouldn't have to force these check boxes to stick by going to the pop up configuration. The check boxes should stay checked when working in the Data tab of the feature service or within the attribute table of the feature service to Show/Hide Columns. Popups are meant for popups, not attribute tables. I'm more interested in this functioning in a table setting. But it doesn't. AND what if I do want people to edit this layer using the rest service, this Visualization tab long way around no longer holds those fields visible as stated in your reply above, correct? BUG??