.dtl settings are drawing settings and are not available in the config.pro files.
You will need to add the .dtl setting to the drawing setup file.
In the drawing you want to change, go to file - prepare - drawing properties - detail options change. This will add the drawing setup option to that drawing only.
If you want to change the setting for all newly created drawings, you will need to add the option to your drawing setup file that is called out in your config.pro under the option drawing_setup_file. AND/OR you will need to change the option in your drawing template, if you use them.