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.

Out of curiosity, are you using WiFi, and what frequency?

A little while ago I had an issue where my controller would interfere with my 2.4GHz WiFi and make my computer basically unusable for online games. This isn’t really the same situation but I imagine something similar could happen in reverse.

Otherwise I’ve never had any issues with controller latency though. It’s weird that it’s so significant for you.

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.