Make selected users more noticeable by pinning them to the top of the comments section.
Click the 📌 button next to the commenter you'd like to pin to the top.
This script will only pin comments that YouTube has requested from the server, which includes comments that are loaded as you scroll down or sort by newest/top. On mobile, you may need to expand the comment section to load more comments.
This script can be installed in Google Chrome without a userscript manager: