HTC 3125 / Smartflip / 8500 (Star Trek)
external keys + ringtones
and another question, where's the volume for ringtones?
Both of your questions can be fixed by going into the phone's settings. The external keys can be locked by default or after a period of inactivity. The volume of ringtones is controlled by editing the active profile.
I don't have my phone or the manual in front of me, but you can either browse the Settings menus or read the manual on those subjects.