How to turn on passenger airbag Subaru Crosstrek?

There's no manual method of turning on the passenger airbag on the Subaru Crosstrek, as it'll come on automatically when it detects that there's actually a passenger sitting in the seat there. If the person sitting there is too light, the airbag won't be engaged, as the thinking is that if the airbag deploys, it'd do more damage than good for a small child, or, apparently, a very light adult. If a normal weight person sits in the passenger seat, and the airbag light doesn't go off, this is a malfunction, and You should take Your Scooby into a dealership as quickly as You can, if You often have other occupants sitting there; this is a serious safety issue.