iPhone 4S: Adjusting VoiceOver volume during a call?

On the iPhone 4s, how do you adjust the volume of VoiceOver while on a call, when using the keypad, End button, etc? My dad has somehow gotten his to be softer than it was and can't figure out how to make it louder. Just using the side volume buttons while VO is speaking doesn't work. Thanks for any help.

Forum: 

#1 That's strange.

If volume is available in the rotor, you might want to try adjusting it there. If it's not, you can add it by going to settings/general/accessibility/VoiceOver/rotor and selecting volume by double-tapping it. You can also double-tap and hold on the reorder button next to any item and drag it up and down. This will move it up/down in the list, which will affect its position in the rotor. Hope this helps, Shersey