Answer the question you can see them typing
Search used to be a string of keywords. People now ask full questions, including inside YouTube’s own search and newer conversational tools. Your title, description, and the words you actually say should match that question in normal language.
Look at your own search terms report. Make the next video for a phrase you almost rank for, or a question the comments keep repeating. Say the phrase once, clearly, near the start. Then answer it. Repeating it ten times does not make you more relevant. It makes you sound broken.