Do it for one of them. Copy the Event by using CTRL+C, select all Events, right-click one of them and select "Paste Event Attributes" from the right-click menu.
Alternatively -- especially if you have other event-level changes that you don't want pasted -- just save your project to a VEG and then bring that VEG into an empty project. Vegas treats it as a single event you can then Pan/Crop as usual.
(Assuming you're using a fairly recent version. The ability to nest VEG files was added in Vegas 7, I believe.)
Thanks a lot. I am with Vegas Pro. I wondered it would work for the sound as well. Some envelopes with my voice are lowder than the others. But it seemed not to work for that. I haven´t changed the voice recording settings. I´d appreciate your additional suggestion.
You can, however, select multiple audio events and then drag the volume envelope in one - working for all - but only until one of the envelopes comes up to 0 db.