We have 2 audio issues with our 2018 Limited. First, we have never been able to preset the channels (am, fm, or Sirius) and have them hold. They stay set while the car is on but either go away the next time the car is started or maybe 3 times later...but they always go away and default to some other set of stations (maybe the original ones, who knows). Also the 4th preset always says "hold to set". It never holds a preset. We have done a UConnect update, cleared the stations out manually, reset while driving and while parked, et to no avail. We have to turn the dial or use scan to find a station. Our dealer told us that maybe the radio is bad but "so sorry", now the car is out of warranty and it will cost $250 to check it out and more if it needs replacing. The second is that periodically we have a high frequency pitch that emits from the radio an gets louder or softer depending on the volume dial. It doesn't happen often but it will continue until the car is turned off and then sometimes will continue even after the car is restarted several times. This happens when using any radio setting but not with apple play or hands free phone via UConnect. Both issues are very irritating. Any suggestions?