Screen record a video of the process? Then you’ll have a video guide, plus you can take screenshots of the video for a written guide.

11.5 what? Data doesn’t really mean much without units.

This may not be exactly what you’re looking for but have you considered using Firefox containers, automatically logging in to a different Google account for each container? I’m fairly sure this would work on mobile (probably only Android though), and is almost certainly more convenient and polished than a separate YouTube client.