You sort of do both. First you create a stream on youtube. ie go live. If this is the first time, you will be asked to create a stream. You create it and get a stream key. Give it a name like "mystream 1080p". Set up the other parameters like size =1080p etc. Go watch youtube videos on this subject. Once set up, you will see that the start stream button is dim, you can't start. Use the little eye thing next to the key to see it. Select the key and copy it using control c. Go to obs, start it up. goto setting and and then select stream. under service select youtube. under server select "primary youtube ingest server". Under stream key, paste in the stream key you got from youtube. Use the show button to verify you get the correct key. hit ok. At this point obs can stream to youtube. you might want to set the bit rate on the output panel to the same you selected in youtube. If you are tranmitting 1080p this is 4500mps, if 720 this is 2mb. If you have a slow internet service, you might adjust according. Make obs to start transmitting. Go back to youtube. You should see something that saids "excellect connection" the start stream button should be visible. Push it and you are streaming. In review, go to youtube.Create new stream. setup,get key. goto obs.use that youtube key in stream panel. start obs stream. Go back to youtube. Start stream there. Stream will appear in you youtube channel. Essentially that key you got from youtube is the key youtube listens to/for. obs uses that key to say hello, got something for you. like a telephone number.DOes that make sense. You will really have to google and watch youtube videos to understand all this.
