You created a line item in a Display & Video 360 mobile web campaign that accidentally targets mobile in-app. You remove that mobile in-app targeting at the insertion order level, yet the campaign in continuing to target mobile-in app. What’s the issue here?

It’s impossible to modify existing line item targeting at the insertion order level.
It’s impossible to modify insertion order targeting at the line item level.
It’s impossible to modify targeting once the campaign has line items assigned.
It’s impossible to modify targeting for mobile in-app inventory at the line item level.

The correct answer is:

It’s impossible to modify existing line item targeting at the insertion order level.