A Dolby Atmos input bed can be 2.0, 3.0, 5.0, 5.1, 7.0, 7.1, 7.0.2 or 7.1.2. Distribution of the bed in the output stage is defined by the number of speakers in a particular room. For example, if a room is configured with no center speaker for playback purposes, a 3.0 and greater bed configuration will try to phantom image the content in the bed's center channel to the available Left and Right positions. This is further accentuated in the overhead domain. Overheads in a x.4 configuration will create a phantom center of the x.2 component while in an x.6 overhead configuration it will use the point source speakers.  If you have a concern about a source in the overhead beds, try switching it to an object so you can have more control over how it renders.