Thanks for joining us here in the Community, yshao.
It's my pleasure to offer some info about changing the display in certain areas of QuickBooks Online.
So I can give you the best advice, would you mind providing a few more details about your request? If you're able to send a screenshot of where you'd like to change the word Quantity, that would be super helpful.
Additionally, certain names of items in the system vary depending on your company type and customer label that you have selected. For example, if your "customers" are labeled as Donors, you'll then have the ability to track donations. These settings can be checked and adjusted by:
1. Clicking the Gear icon in the top right corner.
2. Select Account and Settings.
3. Choose the Advanced tab on the bottom left side of the screen.
4. Company type can be changed near the top of the page by clicking the small pencil icon in that section.
5. You'll find the Customer label in the Other preferences section at the bottom of the page, and you can choose the pencil icon to adjust this as well.