To set you Custom Partslist as your default Parts List - go to Open/Create a new drawing>>Format --> Styles Editor>>Expand "Object Defaults" and select your ObjectDefault">>Search for "Parts List" in the "Object Type" (first column)>>Change the "Object Style" (second column) to your Custom Partslist. You can also choose your Parts List Style just before you insert a PL in your drawing from top-right combo box.