Was the audio changed in a audio editing app? Is so, did you right-click the event and select "Open copy in audio editor" ,, or.. "Open in audio editor" ?
'Open copy' creates and new 'Take' event/file placed over the top of the original. Multiple 'takes' can be toggled with the "T" key (to compare and/or choose the before and after takes.
"Open in audio editor" opens the event's entire file in the audio editor which will be 'destructive' editing and any changes will be permanent if it is saved (overwritten) in the audio editing app.

Adding a sub-project to VP's timeline is refereed to as "Nesting". Any changes to the sub-project will carry-over to the the main project. Off-hand, I do not recall if the main project needs to be refreshed or re-opened if it is already on-line.

rraud, Magix forums moderator

Thanks for all this help. I'll be much better in managing sub-projects in future!

What I had been doing was to edit the sub-project as a separate .veg project, but then to render and import the rendered file into the main project. The audio where the problem occured seems to have been from an earlier version of the rendered file

I am now importing the sub-project into media as a .veg project (not the rendered file) and it seems that the main project immediately notices the changes: for example, if the sub-project is shortened, I can see that in the main project towards the end of the clip the triangle indicating that the clip is being repeated (because it's shorter than the allocated space on the timeline in the main project)

I'll spend some time learning the 'take' concept. In the past I've edited audio files, saving them as new tracks and then switching the audio of the original clip. But this is obviously not the way I should be doing it!

Many thanks again :)