The trims are designed work with limited speaker layouts that consumers would hear with legacy non-Atmos setups (stereo, 5.1 and 7.1) and Atmos speaker layouts with only two elevation speakers (5.1.2). These trim values are written to the master file and used during the encoding process when creating the 5.1 Core of Dolby Digital Plus with Atmos Content. These can be left set at their default values or manually edited in the Mastering Suite for greater artistic control. To monitor edits made to 5.1.2 layouts you will need to create a 5.1.2 monitoring layout in the room setup.   Note that trims are applied to the entire master and can not be dynamically adjusted scene-to-scene.