Sony WEGA TV problem

I can't get rid of the on-screen AV channel indicator (top left of screen).
I've tried the button with the cross inside a square, but this only cycles
through the screen size options (widescreen, 4:3, etc). I've tried the
button with the right-pointing arrow into a square, but this cycles through
some other screen options. The set is only used on AV mode as I only have
Sky.
Anyone got ideas as to how to get rid of this indicator.
TIA
Iain


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