ringtone

I'm on about my third day with this phone and though there's some learning to do (maybe Android version or the fact it's my first non-Motorola phone) so I won't ask about those yet. However the one thing I see so far that seems to be a glitch or issue is that the ringtone keeps changing back to...

I have no idea what is causing this, but when I have an incoming call, sometimes it keeps vibrating after I've answered the call. So while I'm trying to talk to the person, the phone keeps vibrating in my ear. Very annoying. At first I though, since I have Hangouts Dialer installed, that my...