Open Inventory Management, Setup, Product Line Maintenance.
Click the Lookup icon to bring up the Product Line List and select the appropriate Product Line.
On the screen, change the settings you wish to change. You will NOT be able to change the existing-item Valuation or Units-of-Measure fields. For the example of changing the Sales Tax Class, click on the Sales Tax Class box, enter the appropriate Sales Tax Class.
Click the Apply button and another screen will appear so you can choose selections changes to make. You can change 20 of the settings, but not Valuation or Units-of-Measure fields. Product Line Maintenance allows you to change a variety of settings for ALL Items set with that product line, or a Range of Items which are set with that product line. You can also choose whether to update items on open sales orders and on open purchase orders. After making your selections, click Proceed.
The program will then ask you to confirm with the question: “Do you want to apply the product line information?” dialog box, click Yes.