Are you also trying the Editable Notation mode? The lines there represent an eighth-note triplet duration when set for Triplets. Two lines (unsurprisingly) fetch a quarter triplet. In that mode, triplets snap onto the time line automatically without setting anything, and durations self-adjust. You see the final appearance of notation without shifting views.
It's important to remember that BiaB will simply refuse to write triplets in some circumstances, due to ancient, ignored bugs. For example, the program utterly botches triplets spanning the second and third beats of a 4-4 bar. It won't hear of that and goes all brain-damaged. Don't be shocked.