I don't use the account to stream to YouTube. My OBS is not logged into anything at all. Which means I need to do all the management directly in YT, which is fine with me.
On YT's streaming dashboard when it's ready to go and showing you a stream window, chat, and live metrics, all blank because you're not running yet, there's a page of settings too. One of those is a stream key. Copy/paste that computer-generated gibberish into OBS, and start streaming. YouTube will catch it, and there you are!
Some people have called it a security risk to use the stream key, because anyone who has it can stream to your account. Nothing else required. But when you see what the key really is, it should be clear that nobody's going to guess it! It's like a really strong password. And if someone does end up with it somehow, you can generate another one from the same settings page, and paste *that* into OBS. Then you can keep going like nothing happened, and the old key won't work anymore.