Are you looking for artifacts in OBS's Program window? Cause that's what the encoder *receives*, not what it produces. No encoder setting will affect that.
To see the effect of the encoder settings, you have to look at the stream or the recorded file, keeping in mind that the recording may or may not use the same settings. Default is to take a copy of the stream output and dump it to a file as well, in which case the stream settings affect both, but you could also have different settings for each, which doubles the workload because it has to encode twice: once for each destination.
And you also need to let it run a while to "stabilize", before judging the quality, as a big part of the encoding function (and therefore the settings) has to do with the *difference* from one frame to the next. Encoded video is not a series of independent images. 30 seconds is usually good.
