I can see how a two-way integration of items is helpful, lhrt.
The integration between QuickBooks Online and Square has its own limitation at the moment. You'll need to update the quantity of the product in Square first. QBO will then mirror the information once we receive daily updates from them.
Feel free to know more about Square and QuickBooks Online integration, you can use these articles for reference:
Just keep me posted if there's anything else that you need help with. Take care!
