Routing audio to built in speaker doesn't work

Hi,
I have the app RoboVox and i want to force the audio to the built in speaker. But it doesn't work...
Using the setting media audio: Speaker
For that i use this cable: Cable/jack, 1x 4-pin, 3.5 mm > 2x 2-pin, 3.5 mm (Manufacturer : HAMA
Factory number : 115055, For connecting a PC headset to a 4-pin jack socket (e.g. netbook/tablet PC/smartphone)

Some suggestions how to solve the problem?
Once it works after deinstalling soundabout an both outputs works at the same time..i connected it to a external speaker an an the internal works also..but i don't know why and i tdoesn't work a second time.
Phone is a MOTOG 3 G 2015 with Lollipop

Thanks for help

I'm guessing that you are plugging in a headset with a built-in microphone but you want the phone audio to come out of the Built in speaker?

Set the SoundAbout "Media audio" setting back to "Let app decide".

The latest Beta has a new widget called "Wired Mic Toggle". Place that widget on the home screen.

When you press that widget and turn it on, it will use the 3.5mm microphone but NOT the speakers attached to the 3.5mm cable. This means you can plug in a wired headset (with mic) and use the microphone but have the audio come out of the phone speakers or a Bluetooth device.

Latest Beta here:
https://soundabout.forumotion.com/f8-download-beta-versions