Adjusting the initial audio volume in the WordPress default Playlist creator.
Go to the web site’s server and find the folder:
/public_html (or folder with WordPress folders)/wp-includes/js/mediaelement/
Locate the File name:
Using Ctrl+F, search for – startVolume
There should be two (2) instances of the startVolume:0.8 entry. It appears that “0.8” refers to 80% initial volume. If you want 100% volume at startup, change “0.8” to “1”. If you want a different percentage, change “0.8” to “0.5” for 50%, “0.3” for 30%, etc
It appears the startVolume entry affects video and audio seperately. The first entry seems to relate to the volume of the video player and the second adjust the volume on the audio player.