Try updating the software on your phone to the latest version. Annoying “glitches” like a tenacious headphone icon are sometimes caused by an outdated software version. Also, see if doing a full factory reset of the phone’s operating system doesn’t help. These can be done in the phone’s Settings.
If you phone is not working with a certain 4G network, then it may need a PRL (Preferred Roaming List) update to make sure it’s connecting to the right cellular towers. This may also be done in the phone’s Settings.