Also note your picture is now part of that picture/video feed tab in amethyst, whereas your other post are not because they are sticky-notes (kind1) with pictures, instead of explicit picture events(kind20).

As for the redering, i.e. 1 picture being horizontal: this is a choice amethyst makes. Other apps might decide to display it completely differently, it is not something you can controll really. Someone could make an app where they would all be spinning around, or display them in some VR gallery as if they are paintings on a wall, or as little portraits inside a clowncar...if that makes any sense.
You are not ON amethyst, you USE amethyst to produce a publication, that can be viewed and commented on with a large variety of apps.
Nostr.