In the ArcGIS Instant Apps Nearby template, the user can configure the 'Search units' parameter in the Express panel only if the 'Map extent' search method is selected.

Workaround

1. In the Nearby section, under the Search method, select Search Radius for the search method.
2. For Search units, change the configuration from 'Kilometers' to 'Miles'.
3. Publish the app.
4. Once again, under the Search method, select Map extent for the search method.
5. Publish the app and launch it.
6. This time the results will be retrieved in Miles.

Steps to Reproduce