How to remove youtube logo from header video?

Hey guys I've been trying to remove the hover: youtube logo from the bottom right of the header youtube video link. Using Chrome Inspect I found the css for removing the play button however doesn't work for the logo. PS. When I write a display:none code directly in the browser under the css .ytp-watermark works perfectly but doesn't work on CSS ADDITIONAL TAB. Remove Play Buttom (WORKS) .wp-custom-header-video-button { display:none; } Remove Youtube logo (NOT WORKING) .ytp-watermark { display:none; } Any help? Cheers