Sorry to hear that you're having trouble. There are many possible causes for audio distortion and the only way people here on the forum can help is if you can provide a lot more detail about your clips and project.
To start, please follow the steps to create and attach the DxDiag test results from the Read Me Before Posting
guide so we can see the technical details of your computer.
Next, go to the the MediaInfo online
tool and drag one of the clips you're having trouble with there. Click on the
Download MediaInfo report button and attach it to your reply so we can see the specifics of the clip. If you're comfortable sharing the contents of your project here on the forum, you may also want to attach a clip so other people can work with it on their systems.
Finally, make a screen recording showing what happens when you preview the project timeline so we can see and hear what you're experiencing. Attach the recording like the other requested items or upload it to YouTube and paste a link to it here.