Just been having this issue lately where my custom ringtone and notifications change to the default after a reboot or after I connect micro usb to add files to the memory card. I cant seem to find a way to fix this. Just wondering if anyone has had this issue and how to fix it. Thanks in advance.
Try adding your phone ringtone / notification sound this way
Settings-sound-phone ringtone-menu soft key-more ringtones-add ringtone
Then select the ringtone.
Also the similar way for notification sound..
This way you might not lose your custom ringtones when rebooted
sent from my blazing fast pyramid through sonic waves
That's how I assign them. I don't have the issue of losing them when rebooting, but I do have problems when I've connected my phone as a mass storage device as with the SD card unmounted (so it can be accessed by the PC) the phone can no longer see my ringtone/notification sounds.
Annoyingly downloading ringtones from HTC doesn't save them to the phone memory.