So I had been using an app for quite some time. Today I updated it on the iphone, and the new version is annoying with flashing ads on the top. So I put the saved old .ipa file in the itunes mobile applications folder and sync with the iphone. But its giving a message that you are not authorized for it on this computer. I had recently reformatted my computer and copied the saved version from external drive to itunes folder. Any suggestions on how to resolve this issue?