Editing User Extensions
Changing User Extension settings is a little different to other Blocks (where you double click the Block on the call flow map), instead you access configuration from the Block Library. Important: Double clicking any User Extension Blocks you have dragged to the canvas will only change the Ring Extension which just points to User Extension.
To change User Extension settings;
Change to
Edit Mode by clicking 'Edit' on the top left of the workspace.

Click 'Edit'.
In the
Block Library to the right of the workspace click the
gear icon to open up the
User Extension settings dialog.

Click the gear icon to open settings
Then the
User Extension settings dialog will open. Make any changes need, then click
Save 
Route calls to VoIP line and Save
Now to activate the changes you have made you will need to click 'Apply Changes'.

Activate the new Extension with 'Apply Changes'.
User Extension Topics