在 Display & Video 360 中，您的同事为其客户在移动网站上投放的广告系列创建了一个订单项，但错误地将其定位到了移动应用内。之后，对方进入定位设置部分并在广告订单级别移除了这一移动应用内定位，但该广告系列仍会定位到移动应用内。 为什么会发生这种情况？

The correct answer is that you cannot modify existing line item targeting at the insertion order level. In Display & Video 360, targeting settings are hierarchical. While an insertion order can set default targeting that line items inherit, once a line item is created, its specific targeting configurations are managed at the line item level. Changes made to targeting at the insertion order level will only apply to new line items created thereafter, not to existing ones. To correct the mobile app targeting for the existing line item, your colleague must edit the targeting directly within that specific line item's settings. Incorrect options: "You cannot modify targeting for in-app mobile inventory at the line item level" is false; in-app targeting is configurable at the line item level. "You cannot modify targeting once a line item has been assigned to a campaign" is false; targeting can be adjusted throughout a campaign's lifecycle. "You cannot modify insertion order targeting at the line item level" is also false; line items can override or refine insertion order targeting.