For the most part, it's recommended to leave the audio effects alone, with the notable exception of captioning. For accessibility, captions are required on any video with voice narration. There are two recommended ways of adding captions to your video:
See below for more detail.
Begin by adding captions to the audio track in your timeline, as seen below. The audio track might be on its own or combiend with video. In either case, audio tracks can be identified by the audio levels shown in them on the timeline.
After that, an audio track split up into little sections will appear on your audio track. Each section will be a separate caption. Clicking on any particular section will allow you to type in the text. You can change the length of each caption by dragging the divisions on the track or using the slider above it.
Setting your video to auto-generate captions is relatively simple. Just make sure that the language is selected to English and as long as the video is posted publicly, the captions will generate themselves.
To set this up after the video has been uploaded, follow these instructions:
1. Upload video to YouTube
2. Click on your user icon in the top right corner and select "YouTube Studio"
3. Once there, look in the bar on the left of the screen for "Subtitles"
4. Once there, look at the "Languages" column. If you click on an entry in that column, it will show you the assigned languages. Below, we can see that English is selected for the language for my video, and on the right it tells us that subtitles are set to "automatic."
5. If there isn't a language selected for your video, you can click on the video title where it will take you to a page where you can add one.
For more information, see this step-by-step tutorial from the OET.
Audio Compression - Allows you to fine-tune the audio levels on your movie. This isn't really recommended for new users, but can be helpful for making audio clearer / louder.
Noise Removal - This isn't as helpful as I wish it was, but it can be useful for cleaning up some background noises.
Pitch - Unless you really have issues with the sound of your voice, I'd recommend leaving this feature alone.
Fade In / Fade Out - This is helpful when you're using a soundtrack, but otherwise doesn't offer much.
Clip Speed - This has some helpful applications, primarily speeding up demonstrative clips