I too have exactly the same problem. I followed some advice from a different forum to log out of my Apple ID via settings and reboot although upon attempting to log back in to my apple ID I found I wasn't able to. No error messages or anything - just won't allow me. Again my partner runs her iphone on my ID and she can download apps without a problem. It just seems to be my device. When attempting to download a free app the "install app" and "free" buttons appear to overlap and very briefly flicker between the two. I don't recall changing my IOS version manually as I'm not actually sure how to. I'm not sure if a tweak I have downloaded may do so for me, but could anyone explain how to set my IOS back to the version it is supposed to be? I figure if I balls it all up I'll just have to restore my phone - again, it's not something I want to do but at the moment appears to be the only option for me.
Thanks in advance
Thanks in advance