Looking to add audio points to be able to vary audio level in voice overs areas..
Vegas Pro16 Edit
Assuming VP16 is same as previous versions... Select the track you wish to add an volume envelope. In the menu select, "Insert> Audio Envelope> Volume" (keyboard shortcut "V"). Right-click on the blue volume envelope line where you desire a volume change and select 'Add point' (shortcut: double-click to add a point). Two points are usually needed for interpolation. (see example screenshot below). Drag the points and/or the envelope lines up/down. Right-click an envelope point and select "delete" to remove it. There are other ways and techniques in the user manual and on-line tutorials..
example:
If you make a selection across a voiceover area, you can simply drag the volume envelope and it will give you 4 points that are a good starting point:
