Audio normalization across multiple clips and for Youtube, in After Effects
Your workflow is wrong. You just don't normalize audio with After Effects. Instead either do it with an audio editor, like Audition (which seems suitable to match clips in timeline, just use the normalize effect and maybe a compressor if the dynamic is too great). Finally apply loudness normalization with your video editor. For example during export with Premiere Pro you can set the loudness in the effects tab. Choose a profile and set parameters. For background information on parameter and unit names you can read a PDF here.