you cannot use the standard tv options since probably you have configured the Bravia sync on (that by the way is not supported by mysky. 

You have to options:

• disable the bravia sync
• leave it enable, and press the sync menu buttonon the remote while whatching sky, the select the "use tv remote to control tv" (or something like that): in this way all the command send by the remote will go to the tv and you can now select option and change scene/image settings