990 speaker identification

Hi all, here I am in 2023 still using my 990. I have a 976 running my surround sound in my family room, 990 relagated to running my office sound IN STEREO. I only have two large speakers attached but in setup it says I have 4 speakers, 2 front and two side. When I try to use the speaker size menu, it does not let me change the side speakers to NONE. Just Large or Small. Is this a known bug? Don't know how it affects anything but my concern is if I use any VIRTUAL sound attributes it may try to pump sound to the sides that do not exist. Any thoughts from my old 990 friends?

As long as you select two-channel stereo for your "Surround" mode, all sound will be sent to your two speakers and nowhere else.