To Set a Custom Parts List as the Default Parts List Style (AutoCAD Mechanical Toolset)

At the Command prompt, enter AMOPTIONS.
In the Options dialog box, select the AM:Standards tab.
In the Standard Elements list, double-click Parts List. The BOM Settings dialog box is displayed.
In the Parts List tab, in the Default style section, select Custom. The drop-down list next to Custom becomes available.
In the drop-down list, select the name of the custom parts list scheme. To use a custom parts list scheme from an external file, select Browse and open the external file.
Click OK until all dialog boxes close.