Plex "Metadata Agent" vs "Source"

[paterson37]

Sorry if I'm being a bit dense here.

In the good practice part of the instructions it states;

Using default Plex Movie and Plex TV Series metadata agents improves script compatibility (for matching or for watchlist). It is recommended to migrate to the new Plex TV Series agent.

And below that it says

Use tmdb as source for TV Shows if possible, because it's the Trakt primary data source (switched from tvdb in Jan-2021).

I'm asking because I'm getting a lot of errors of either "Provider Local has no external id" or "Not found on Trakt". The shows not found on trakt I know are there after searching.

So I set the metadata scanner as Plex TV Series. Change the Agent to The Movie Database but then that changes the scanner to Absolute Series Scanner.

Is the source located somewhere else in the Plex settings?

Thanks in advance folks!