Force the phone app to close after a call either after receiving a call while the phone is locked or after making a call? I find it annoying to wake my phone up and have to close the app.
I've fiddled around with the settings a little bit and I can't seem to get it to work either. There is a support web site listed at the bottom of the settings screen for the app. You might want to take a look there (as will I).
Edit: I hope you speak french, because that's the language the support site is in
I already went there and couldn't find a way to change the language to english. I used a translator but no help there either. I sent a tweet to the developer.
I don't get it what are you trying to do? If you use the headphones you could just click the mic to start the iPod which closes the phone. Then just pause the iPod again it takes like a second.