If you are using the Thread command then simply select 'Symbolic' as the Thread Type. You must do this for every hole. If the detailed threads already exist, then you need to delete each thread feature and create a new Symbolic thread. Because this is a very old command which does not use a block based UI, the edit dialog is not the same as the create dialog.
Better yet, you should always use the hole command to create threaded holes.
There is no global setting to show detailed vs. symbolic.