The answer might be misinterpreted, so some clarification:
You can have .dtl files on disk. You can set the config drawing_setup_file to point to one, and it will be retrieved when making a new drawing. Having .dtl files on disk does not change your drawing's appearance. In the drawing, File>Prepare>Drawing Properties>Detail Options, Open can read a .dtl file and change any detail setup options in the drawing as instructed. When making a start drawing (which you will later use with File>New>Drawing>From Template), getting the desired set of detail setup options to match your company's standards is an important step.
In each drawing, there are detail setup options. These can be different from drawing to drawing. You may for example open an ISO standard drawing and an ASME standard drawing in the same session, and naturally you would want each to show according to its own standard. Generally speaking, if something would logically vary by drawing, and/or would affect stability of a retrieved drawing, it'll be a detail setup option. If you change your company's standards, released drawings will not be modified unless you run a batch process to retrieve, set the new option, save them. In recent releases, solids also have detail setup options, to support MBD.
Config options are session-wide, and have behaviors that aren't going to change from one model to the next.
