Volume does adjust itself on this device, hopefully will get fixed by coders, if it is, there'll be an OTA with it included.
In the mean time, it shouldn't drop the volume by more than a few steps, if it is then as David suggested, if you have a remote control that moves the on screen cursor when it is physically moved through the air, flip it so the QWERTY keyboard is showing, and put down on table, see if this stops the volume being adjusted a lot.