iPhone X changes ringtone itself

Are you running the latest iOS version 11.3.1? If you aren't, update your phone. This was an issue when iOS 11 first came out, but seems to have been resolved in the latest update. And it would also be advisable once you've updated to open Sounds & Haptics > Pick any tone > Tap Download All Purchased Tones > Then reselect the tone you want.

This has worked for some (me included) but not for all..you may need to re-download your ringtones

Go to settings > Sounds and Haptics > Ringtones

If you need to do this, under the Tone Store will say ‘Download Purchases’. Click on it and you should be good to go. If you don’t have that option, I’m at a loss. Good luck

(The pic is of where the ‘Download Purchases’ should be. Mine doesn’t show it any longer because I had already downloaded. If you don’t have downloads, it will look just like the pic)

Use tones and ringtones with your iPhone, iPad, or iPod touch - Apple Support

So every time someone calling you, the ringtone is another? Try reset your iPhone by holding both buttons > on/off and home. If this not help, try restoring your device.

This is my 2nd Iphone X, first was replaced because of this and other glitches which I was able to show the Apple store at the time. However it is now doing this with my new phone. I am running the latest IOS 11.4.

What else can we do to fix this?

my iPhone X has started changing its ringtone by itself but when I check the settings it has the same ringtone I’ve selected. If I try to change the ringtone it makes no difference. The only way I can get it to turn back is to switch the phone off and on again. Anyone know why this is happening of how to fix it?