Going through each item would be inconvenient, NBenavidez. You won't need to do that.

When you add an item, you'll notice that the Income account is defaulted to Sales of Product Income (inventory) and Sales (non-inventory and service). Then, for the Expense account, the defaults are Cost of Goods Sold (inventory) and Purchases (non-inventory and services). You won't need to go through each item. Unless, you have one item that will use a different account.

We're unable to change the default income and expense accounts of the items. However, you can change the Detail Types these accounts. Example: For the Sales account (non-inventory and services), you can change it's Detail Type to Service/Fee Income if you want your service sales to be reported that way.

Let me know if you have other questions about your item's accounts or setup, or anything that will make your records perfect for your business.