To change the field name in the popup table, you can do this in the map viewer on a specific layer. This wont change the underlying table field name but will give it an alias.
Open Map viewer, click on the layer, click on the ‘fields’
To configure the search function in an AGOL app so you can search on a specific table field, open the App Configuration and add source
Select the layer source and the field which contains the data to be included in the search
To enable the map user to add picture attachments to a feature layer, go to Overview section of feature layer.
Then go to Layers and enable attachments
