Taleo career section Candidate applies from social media but picks up a different source

Summary

Taleo career section Candidate applies from social media but picks up a different source

Content

Hello ,

In External career section ,We have candidates that connect from An external website pressing LinkedIn Button.
In this case ,we get the candidate gets a submission form with the same source lists to choose ,and he is able to pick up the source which is not LinkedIn but any other source.

Question please -
in case the candidate applies from social media (for example LinkedIn ,Facebook of an external website )
can We hard code or disable or not show the source field to candidates so they can not change their source? Please see screenshots attached.