How To Keep Hands Separate When Recording From Keyboard To Two Staves?

When I use the keyboard controller to input notes, MueScore is placing all of the chord into one group according to the top stave. This is resulting in an inordinate amount of ledger lines below the top stave, and some of the ledger lined notes are even colliding on top of the bottom stave.

It would seem there must be a way to keep the notes in the left hand (lower stave) and the right hand (upper stave) separate. But I dont know what this technique is called.

The piece I am writing is in four or five part harmony. So it would usually follow a B|T|A|S or B|T|A|MS|S voicing structure depending on the measure.

Any helpful pointers much appreciated!