sound for mail notification won't change

Hi.

I have an iPhone 5c with the latest iOS update. I've noticed a problem when I try to change my sound for my mail notification. When I select a new sound in settings, it won't update. I've tried selecting the old sound I had and then selecting a new one, but it doesn't change.

I do not have a problem changing any other sound notification setting. Is anyone else having this problem?

I noticed this before the latest update but have not had a chance to post about it. Any help or suggestions will be appreciated.

Thanks,

Becky Manners