Welcome to the forum.
In your Project, set up to match that Video, I would just Import the Music file (PCM/WAV @ 48KHz 16-bit would be the best format), and drag it to Audio Track 2.
To turn OFF the Audio from the Video Clips, I would go to the Audio Mixer, and just check Mute, for the Audio Track with that Video's Audio Clips - probably Audio Track 1. If you will tell us which version of PrE you are running, someone can tell you where to find the Audio Mixer for that version.
PS - you can use the Translate button, to translate my post to the desired language.
Please say what version of Premiere Elements you are using and on what computer operating system it is running.
From what I have read about what you want to do, you do not need the audio mixer.
1. Right click your video that has audio linked to it and select Delect Audio.
2. Import your music with Add or Get Media/Files and Folders, and, from the media area, drag it to the Timeline Soundtrack.
That is the basic idea.
If you obtain your music from iTunes, you may have to convert that music iTunes to .wav (preferred by some) or .mp3 before you import it into Premiere Elements.
For more specific answers with details, we more details specific to your situation.
Looking forward to your follow up.