Follow the steps below to change your default media player on an Android device, for version 4.3 and higher, this could also apply for other versions as well, it just hasn't been tested.
Step 1 : Press and hold the home button of your Android device.
- This will show a menu like feature with options. Amongst the options is the "Task Manager" item with a circulat, piechat icon. Click on the item
Step 2 : Upon selecting the "Task Manager" option, you will be redirected to a "Task Manager Window"
- On this window, you will notice several tabs at the top. Amongst those, there should be a "Clear Defaults" tab.
- Select the tab, there default apps should be listed in the window below the tab.
- Click clear on the right hand side of the app you want removed from the default players.
After executing step 1 and 2, the default media player should be changed.
:) Also refere to this URL : http://skp.samsungcsportal.com/integrated/popup/FaqDetailPopup3.jsp?cdsite=ca&seq=446380 for clearing memory on your device.