Open YouTube and find the video with the audio you want
Copy the video URL
Use a YouTube-to-audio converter or downloader that supports MP3 or M4A
Paste the URL into the converter
Choose the audio format and quality
Download the audio file to your device
Trim the audio to the ringtone length using a ringtone editor or audio editor
Save the trimmed file as an MP3, M4R, or other ringtone-compatible format
Transfer the file to your phone if needed
Set the file as your ringtone in your phone’s sound settings