On the web interface:
- Click your user icon in the top right.
- Select Your Data in YouTube (it’s below Settings).
- Under the Your YouTube Dashboard section click More to expand. (You can view (but not search) your comments here.)
- Click Download YouTube Data then follow the Google Takeout instructions, but:
- Click the All YouTube Data Included button and deselect everything except my-comments (or at least deselect videos and music).
Once the download is ready (you’ll receive an email):
- Download and open the ZIP file.
- In one of the folders there’s a file my-comments.html, extract it or open it in a web browser.
- Use the web browser’s “find on page” feature to search for specific comments.
https://takeout.google.com/takeout/custom/youtube will take you directly to step 4.
https://takeout.google.com/takeout/downloads will show you Takeout downloads if you need to access it not through the email.
https://www.youtube.com/feed/history/comment_history will take you straight to your comment history; if your comment is recent you might be able to find it quickly on this page instead of having to download and search the entire history.