I'm here to provide some information about using QuickBooks to manage your inventory.
QuickBooks Online Plus has a built-in inventory feature that enables you to automatically track inventory. Let's first make sure that inventory tracking is turned on in your account. Here's how:
Go to Settings ⚙.
Choose Company Settings.
From the Sales menu, select Edit ✎ in the Products and Services section.
Turn on Show Product/Service column on sales forms.
Turn on both Track quantity and price/rate and Track inventory quantity on hand.
Just a heads-up, QuickBooks always considers the first items you purchase as the first items you sell. Also, there are specific built-in reports that you can generate to see your best sellers, what’s on hand, the cost of goods. I've added these articles for more insights about these processes: