Flat Trills

I haven't been able to create--and this is required for the piece I am plugging in--a trill that goes a step flat, or a trill that goes a step--for example, G to A trill. If there is a way to do this please let me know, because I tried articulation properties and checked inspector to change anything but they weren't in there. Could you please add trills that go a half-step flat and trills that go a step up? It'd really be appreciated! If I need to enlighten you on what I mean just contact me and I'll enlighten you! Thank you for taking my feedback!