Thank you for this, @DougBrowning, and @UriGilad_EsriAu
Perhaps it was my blurry eyes . . . inside the 'configure pop up fields' window there is a space to add a title, description, and then it says 'Select fields' followed by the list of attributes. I thought 'Select fields' was describing the subsequent list (the 'active' attributes, if you will), and was not a button. Once I thought to click, sure enough, the 'turning on and off' options were there. And as you said, @DougBrowning they go to bottom of the list. Would be great to have even have a title change here: instead of 'select fields' 'turn fields on/off", for clarity
*Speaking to reducing time and effort: I have a few suggestions for the ArcGIS team regarding popup configuration (unless I'm missing something!): 1. to make the process of ordering attributes up and down the list a scrolable process (Currently, the number of spaces you can move up and down is limited by the window size (approx 8 attributes displaying); so the process is to drag the attribute every 8 spaces. drop. scroll up. drag eight spaces. drop. scroll up.... making this a very tedious process if, like me, you have 58 attributes. 2. it would be great if you could move multiple attributes up or down at the same time AND 3. if the list could be automatically ordered in the order of, say survey questions, for example (then rearranging would be less tedious)
Thanks again for your help. Very happy to have the ESRI community knowledge and experience at hand.