Video track gets audio track burned into it

What is your operating system?
Linux 12 Bookworm using ShotCut 24.01.28 Appimage

What is your Shotcut version (see Help > About Shotcut)?
ShotCut 24.01.28 AppImage

Can you repeat the problem? If so, what are the steps?
After starting to use Shotcut 24.01.28 AppImage , if i have a simple one video track and one audio track under the video track, after one save/export, thereafter the actual video track has the audio track burned into the video.
In other words if i decide i want to change the background music track / audio…and have made all my edits in the video track,I have to use the Mute on the video track,so my updated audio track is heard ,If i do not mute the video track i am hearing both the previous audio track along with the updated audio track when doing a playback.

Have never had this happen before.
Have used Shotcot for around 10 years now,so am familiar with most of the gadgets and buttons.

TIA

This bug report is not accepted because it is not understandable and not detailed enough steps.

after one save/export

Which is it? Save or Export? They are completely different.

If you are using Export, then yeah, the output file is going to have one audio track with all project tracks mixed together. It has always worked this way and always will.

OK, It was export,

Im not talking about the actual exported video…the Timeline video.(which has no original sound) just for completeness.

PLUS, this is on the timeline the video has the previous audio track ( AFTER) I have done an export…
As i said previously if i change the background audio track only changing the file,not deleting the audio track, …I am hearing both the previous audio track along with the updated audio track,—On the Timeline scrub/play.

Of course if i do an export like this I hear both audio tracks on the export video as well.

Have used ShotCut for ten years,This has never happened like this

It reads like Shotcut let you export to a file included in your project. Is that what happened?