Another thing to check is the screen resolution on your computer monitor.
Right click your desktop.
Click Tab for settings.
Make sure the slider for Screen Resolution is over to the right.
Mine is USUALLY set at 1024x768 pixels (yup - blind).
At this setting not all of the TAR player is visible onscreen.
Switched mine to 1280x1024 for the TAR HD (looks beautiful)
Shows the whole TAR player.
Volume control slider is on bottom right of viewer/player.
Other than that - volume control on bottom right of screen or volume control on your speakers themselves.
Hope this helps.
Jim