When configuring pop-ups for multiple layers, the pop-up data appears in order of smallest polygon to largest polygon. Because polygons vary in size, sometimes different layers appear first. This is vary annoying and confusing when preparing an application for the public. Please order the pop ups in the same order as the layer displays in the table of contents. And when there are multiple pop-ups, change from a right arrow scroll, to a pull-down menu selection, so that the desired data is much easier to find and access.
This idea has been marked as a duplicate of ArcGIS Online - Order Popups same as Legend. Please up vote the linked idea to show your support