YouTube has a number of ways to access a channel. Sometimes the username works, sometimes not. The only consistent method is the channel_id.
YouTube instructions to find your channel ID.
Find your channel ID
You can see your channel's user and channel IDs in your advanced account settings.
- Sign in to YouTube.
- In the top right, click your profile picture Settings .
- From the left Menu, select Advanced settings.
- You’ll see your channel’s user and channel IDs.