ORC - How can we add new source value for "Search Engine" Source Medium

Summary:

We wanted to add the new source value for Source Medium "Search Engine". How can we add this.

Content (please ensure you mask any confidential information):

When we try to add using "Candidate Dimension Source Names" task, we can add it. But it's visible only when the Source medium is "Candidate created manually".

But we want it to display this New Source value for Source medium as "Search Engine". But it's not showing.

And currently it's showing the source value as "Bing, Google and Yahoo" for Source medium as "Search Engine".

So wanted to know how to add new source value for "Search Engine" Source Medium.