Stop watching tutorials made for older versions of OBS.
The only thing you have to do is run the Auto-configuration Wizar and apply the settings it gives.
Please restart OBS and perform a test recording of at least 30 seconds doing as you normally do, including playing games, full camera or whatever you normally do.
Now look inside Help menu. Upload the current log file and paste the url to the log in here. Click on the Analize button to start troubleshooting common issues.
And, of course, the quality you can achive is limited by the hardware you have.