No iTunes Credit Found on iPad

I received a credit from Apple because of a litigation award from the E-Books settlement. The credit appears on my iTunes screen when viewing on my desktop Windows computer. I do not see the similar credit when viewing the AppStore/iBooks/Music on my Apple devices (iPad Air, iPhone 5). I recently made an App purchase via my iPad. No link or box appeared to use my credit, so I was charged full price for the App without an allowance of the credit.

What is the solution? Do I need to make any future App/iBook/Music purchases from iTunes on my Windows desktop computer to use the credit?