I have a 7970 which I deleted two DN from the buttons and moved the others up a spot.
I wanted to remove extension 207 from button 4 and replace it with 209
I wanted to remove extension 209 from button 5 and replace it with 212
I wanted to remove extension 212 from button 6 and set it to 'none'
I made the changes and hit apply and it ran through the update. I then did a refresh and the buttons were the same.
I did the changes a second time and hit apply, then hit ok (it updated a second time even though I didnt change anything).
I opened the voice window again and the phone buttons were back to the original settings again.
I then went into CUE and made the changes, brought up the voice window and the changes were made properly.
I am not sure what went wrong.
I am including the cca log from today.