You don't really need to mess with the quality profiles, the defaults are fine.

All they do is filter the resolution/bitrate. You set a download to look for HDTV-1080p and it'll look for something up to or including that resolution.

Each quality profile also has a size picker with min/preferred/max setpoints, like 3.5GiB/h, so a one-hour video would be 3.5GiB. This is to filter something labeled as 1080p, but if it's an hour long and only 20 MB it's almost certainly a fake, which you want it to skip.