When making a selection in the Collector app your records will preview below or you can choose to see these in a list. Two attributes are displayed. Neither are not the popup title. Where do I configure the attributes that display in the selection preview? In our application it's not uncommon to tap and get 2 or 3 records back. The attributes previewed in the selection set are not distinct enough and require the user to visit (show details) on each record to make sure they have the correct record to edit.
A selected record in collector will show an attribute title and subtitle. As I understand the title can't be configured and not sure what criteria is used for deciding what attribute gets used. The subtitle however is defined based on the layer attribute specified in the layer display tab found in the layer properties accessed in ArcMap (the MXD).
“In Desktop you can set your display field under the layer properties in the Display tab and set the field in
Display Expression. This field will then show up as the subtitle on the results container.” (Thanks Russell)