Can not play chord when using some sound engine

OP-1
1

I notice that I can only play one note at a time when I select some specific sound engine as my syth.

Could anyone explain why some engine could not be played chord with?

Maybe I asked a dump question. Sorry if the question was asked before.
2

depends on the preset, synth then number of your sound then shift+T2 should give you an idea

3

Thank! The setting is "polyphonic "

4


Thank! The setting is "polyphonic "

and the sequencer isn’t engaged?