Why in setting accounts for export of Positive & Negative Inventory Adjustments, the drop-down menu only gives the option of COGS, Expenses & Income?

The negative and positive inventory adjustments are recorded as Expense or Income and not against inventory because you may do a manual inventory adjustment if stock gets "lost" for example. If you access the Help file in QuickBooks as search for inventory adjustments, it will list the process that QuickBooks follows to make such changes. The accounts listed in the help file are the ones listed in AdvancePro drop down for making the inventory adjustments. The change in inventory numbers is recorded in QuickBooks, but QuickBooks will also record the inventory change as a dollar amount because the stock costs a certain value and that must change when the quantity changes.