Where you consume IdP metadata through a federation, any changes to the IdPs metadata appears in the federation metadata and OpenAthens SP will pick up those changes automatically - either when the metadata's
cacheDuration time is reached, or daily - whichever is longer.
Things are different when you add individual IdPs via the additional identity providers option as the function that inserts them instantly into the relevant metadata stores their metadata in a static state.
Should any of the individual IdPs metadata change you would need to remove the entity via menu next to the entity ( ) and then re-add it using the updated metadata. The updated metadata will be picked up by OpenAthens SP the next time it re-caches (no more than 24 hours).
If you need this to happen sooner, you will need to restart the web server component - for new entityies, restarting the webserver is sufficient, for updated entities you would first need to clear the OpenAthens cache before restarting.