Hi aboard2123,

In addition to MikeinBC's answer, you'll have to switch the unit of measure option in the inventory item.

Here are the steps:

1. Click Lists located at the top.
2. Choose Item List, and find the item.
3. Double-click the item to open.
4. Under Unit of Measure, select the U/M Set from the drop-down list.
5. Click OK.

Then, manually adjust the inventory by following the steps:

1. On the Item List page, right-click on the item.
2. Choose Adjust Quantity/Value On Hand.
3. Select the Adjustment Type, Adjustment Date and Adjustment Account.
4. Click the Find & Select Items button.
5. Click Save and Close.

You can also check this article for more details: Adjust inventory quantity or value.

If there's anything else you need, feel free to leave a comment. Thanks.