PSR S770 chord Hold/Decay bass with accompaniment turned on without style

[yuvim86]

Earlier version of Yamaha like psr i425 had accompaniment chord HOLD by default where bass would decay slowly.
But in psr S770 when i hold a chord on accompaniment left side without style turned on,as soon as i release the chord there is no bass decay effect.
Any way to set it,so that bass decays slowly .

In korg similar function:
MEMORY This button allows you to choose whether the Lower notes and/ or chord triggering the accompaniment must remain in memory after raising your hand from the keyboard. On Depending on the setting of the "Memory Mode" parameter (in the Global > Mode Preferences > Style Play), the sound on the left of the split point (Lower), and/or the chords for the automatic accompaniment can kept in memory