I want to have barlines only on the staff of each individual instrument, not spanning across several staves.
The Engravings options has a choice for this in vocal music but not for instrumental (or I have not found this).
How can one do this?
One way you can achieve this, is to put each player into a separate group. To do that, in setup mode select a player on the left panel and click on the add group (fourth icon on the bottom of the panel). It will have however the side effects of instruments of same family won’t be bracketed together.