Annotations that can be included in Annotation features have to reference an Annotation plane. The Annotation plane is a plane that defines the orientation of the annotation item with respect to the 3D model. The annotation item is not actually placed on the Annotation plane, but on an imaginary plane parallel to the Annotation plane, and facing in the direction of the front of the Annotation plane. The actual location of this imaginary plane with respect to the model is determined by the first selected attachment for the annotation.

When you reorient the model, the annotation is also reoriented accordingly. As you look at the model from different views, various annotations will be viewable (and some will not).