Android Audio Path Widget

Select the audio path widget from the Navigation Drawer or while in call. Selecting the audio path widget displays the available audio options for this device.  This will include connected and available BT devices. Tapping an option brings the selection to the top of the list and brightens it.  

Open the Navigation Drawer to see the Audio Path Widget. Tap to expand the widget. It will expand and will open on the default tab (in this case, the contacts tab).

Tap "Earpiece" or "Speaker" to highlight. Note that the selected item brightens and moves to the top of the list.

Make an adjustment to the audio path widget during a call.

A note about Bluetooth devices:  The audio path widget allows you to select the audio path in order of preference.   Bluetooth devices that have been previously paired to the Android device will automatically be reconnected when within range.  The first time a Bluetooth device is connected it will always automatically be the preferred pathway.  After it has been moved down the list , below the speaker phone, it will stay at that priority level when it reconnects.  If the device has been removed, by hitting the "X", then when reconnected it will always go to the top of the list and become the select audio path.  For best practices, don't press the red X, so that the device doesn't take over the audio stream.