The Adsense report system can be a bit confusing at times. I decided to write these instructions after struggling to display daily earnings information for just a single site in Adsense.
The easiest way I found was this:
Select the “entire account by day” report type.
Go to the “search or filter your data” input box and choose “site”.
Choose the site you want to see reported. Hit apply.
Now you should see a daily breakdown for just a single site.