You can use this app to adjust volume in WP8.
How to use this app in WP8.1?
There are no API support for WP8.1 to change volume directly. But if we can get the UVC , we can change the volume easily!!!!!!
STEP:
1, Click the button in this app, it will play a mp3 (10s).
2, Close the screen use power button ,then open it .You will see lockscreen and …. Yes the UVC!
3, Now you can tap the “V” button in the corner to change system and app volume easily!!!
Notice:
Only through the application to modify the volume, can the livetile update!
v5.0 Support WP8.1
v4.0 new UI!
v3.0 you can close vibrate and sound effect!
v1.4 click to close sound,and bug fix
v1.3 add sound effect
WHAT’S NEW IN VERSION 9.4.0.0