I don't use Yahoo, so I'm shooting from the hip here. First, did the app's settings default after the update? I've seen Facebook do it, so I don't think it's beyond anyone else to pull that stunt either. Double check your settings to be sure. Second, assuming your settings are correct, you may wasn't to uninstall and reinstall itThat may clear up anything that carried over by mistake.
Please hit the "like" button if I've helped.