The naming convention of NVS2801 is fixed to
where date code came from the camera and xxx is seq number at the same date, yyyy is random number to protect overwrite.
There are only one possibility of changing the folder name.
Menu -> Setup -> Folder rename
And make it ‘On’.
Then NVS2801 show you name selection window whenever you make backup.
You can change first two character of the backup folder using that feature.