For Xmas, my girlfriend gave me an HTC One , to replace my Old S3, and it's an amzing phone! I do, however, have one issue I've not been able to fix.
On my S3, I used an app from Play to randomly change the ringtone at a chosen interval. I liked to use the MP3 libray I had on the phone to pick a different song for each call. So far, none of the randomizer apps I've tried on the One don't work. SOme just change nothng, while others will change the ringtone listed in settings, and either play the system ringtone, or none at all.
If you've managed to make this work, PLEASE let know how. I get bored easily with it as is!