They seem to have changed controls again.
Click Sites and Applications.
On the page, find your application name and hover over it. The line will be highlighted, and two buttons will appear under the application name - "Reports and Settings Management".
Click Manage Settings. Right below the name of the application, you’ll see the site URL and publisher ID at the top. This is what you are looking for.
PS - PublisherID is the same as adUnitID.
Aditi
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