I can't change my ringtone...

[Keira15Xperia]

It says it's changed, but when someone rings me it isn't 

[MarlonUk1]

can you tell me how you changed your ringtone?

http://support.sonymobile.com/global-en/xperiae1/userguide/Sound-ringtone-and-volume/

does this happen when you are on safe mode

[Keira15Xperia]

I go on call settings then phone & vibration then phone ringtone then I choose one but it doesn't change, well it says it has but it hasn't...