Installing app from google play in my SD Card I like hearing to songs through tuneQ app (Scosche), which I had downloaded from Google Play. tuneQ is a music player.

Unfortunately the player lists songs present in my Internal Memory. I want to install the tuneQ player in my SD card so that I can have access to all the songs in my SD card.
Have you tried the "Apollo Music Player"-app by the CyanogenMod team? As far as I know you cannot read and play music from the external memory if the application is not able to. So you won't fix it by installing the app on the external SDcard.

The Appolo Music Player is:


Free 
Great
Equalizer
High Quality


This cannot be downloaded from the Google Market, but you might grab it from XDA (just be sure to enable to permit installing from unknown sources):

http://forum.xda-developers.com/showthread.php?t=2196385