Make sure you are in the ALLSET PLUS APP (blue or Gold)
Click Live Tv, then find a channel and click on it until it is FULL Screen...give it a second to let the screen become full and the menu goes away
Then on remote press left or right on the firestick remote CIRCLE Button to open up a volume bar in the middle of the screen and make sure it's all the way to the RIGHT
This will make sure app volume is at full