Well, there is a way but it depends on what you are doing. I don't know of a way to do it during editing, but during a disk burn there's an option available.
In the Share screen, when burning a DVD there is a "normalise audio" option. See following image and the check box for it
There's a description of this in the X5 user guide and I daresay that will be in the X7 guide as well, since the function is still there. The brief explanation is that different clips may well have different audio levels and this function adjusts it so the audio level is balanced throughout the final video.
There's a problem with this that's - to me - unresolved since I flagged it some years ago with X5. Basically, with a menu linked to a multi-item disk, that is there are say 4 items on the disk and a menu managing links to each of those items on the disk, choosing to "normalise audio" (check box ticked) during the burn phase creates an output that skips the first item after the menu in the final result. It was repeatable, even with experiments that switched the items in the menu into a different order, but I didn't get any 'fix' response to reporting it. So now I avoid it/don't use it. And with a bit of thought, that is probably the most correct action. Just about every project I know of has varying sound levels in it - eg a soft or muted music background during a voiceover relating to natural sounds in a clip. And the audio between clips may well be intentionally different: the level on a race track would certainly be different from that on a small river. Levelling the sound may well destroy whatever balance the creator has reached during the edit phase.
When I get to this part now, I just invest the effort in getting the audio levels right in each clip, before attempting a disk with menu. Fiddly but without frustration in the final result.
Davidk