Most movies have multi-channel audio tracks, i.e. 5.1 channel or 7.1 channel audio in dts, Dolby or PCM. Virtual surround modes such as “Multi ch. Stereo”, “Dolby ProLogic II Movie” or “Dolby Prologic II Music” are not available (and not necessary) when the source audio is already multi-channel.
It is best to use “Surround = Off” in such cases as it enables the appropriate multi-channel decoder and you will hear audio from all your speakers (in real surround sound) the way it was authored on the DVD or BD by the studio.
Many DVDs & BDs have options within the DVD or BD menu to set the audio output format. e.g. “Dolby Digital 5.1”, “Dolby TrueHD 7.1” “Dolby Digital 2.0”, “dts-HD Master Audio”, etc. depending on how the DVD or BD was authored by the studio. Please use the particular DVD or BD's setup to choose the audio format you prefer.