Please explain exactly what you mean by the external audio cannot be controlled. What control do you wish to have? Assuming you are using timeline view and this audio is on its own track, everything can be controlled in my experience.
I am using timeline view and this audio is on its own track. I do everything according to instructions and yet the music (.wav) in that track sounds terribly noisy, without being able to change anything.
Thank you for the additional information. Unfortunately, I am still somewhat unclear about what you are doing and with what results, sorry!
So, you have your external audio on a separate track. What is this audio, speech, music, sound effects, etc., and in what format is it, wav, .mp3 or...? Have you checked that its sample rate is the same as the audio in your video files, normally 48kHz, and 16 bit?
Can you define terribly noisy? "Noise", in audio terms, is normally defined as "unwanted sound". Is this noise "hiss" or "distortion" or is it simply too loud?
Sorry to ask so many questions but we really do need a lot more information from you if we are to have any chance of being able to help you!
The format is .wav and there is music in it (Classical), and...yes, there was a huge distortion.
But actually, you solved the problem for me, because as you mentioned it should be about 16 bit, while I tried to put there 32 bits! I have changed it and came up with satisfied solution.
Still I have two other questions,
1. Even though I do have the 'volume curve line', I can't create those little nodes along it, in order to change locally the volume.
2. All of a sudden there is sometimes flickering in certain frames. Every time in another area.
Movie Studio should be able to handle standard 32 bit wav files but they require much more motherboard ram cache.
Increasing the amount of buffers in the audio section of the program setup should help but don't increase them by more than double the amount showing to begin with. There are drawbacks to adding additional buffers.
Being 32 bit files they may also have a lot larger dynamic range than standard 16 bit files so may have to have their volume lowered accordingly. This is generally achieved using the method @AAProds has given you.
You can either change your tool on the tool bar to the line drawing tool to draw curves or use a quick double click with the single object selection tool to add a node to the volume curve line. You should then be able to grab and move that node around on the timeline.
[EDIT] You will find a lot more about the use of editing the volume curve on this topic.
All of a sudden there is sometimes flickering in certain frames. Every time in another area.
Is this also resolved or is it still a problem? If so, I suggest you start a new thread and include a MediaInfo analysis of your video file. If you have not used this before there is full tutorial on installing and using it here.
Also, can you check that Windows and ALL your drivers are fully up-to-date on your computer?
One thing I should have made clear: check for any updates for your computer components, e.g., your CPU, at the manufacturer's web site rather than through Windows itself! So-called "Windows Updates" of other manufacturers' hardware/software are sometimes nothing of the sort!