Language setup not setting up

Hi. I have the Classified theme and on the single listing page, when you are looking at a single advert there are three -buttons- Descriptions, Details, Comments, just above the advert.
What I’d like to do is to change the name of Details to a more proper name like Owner, Seller or Advertiser. Changed it in Language setup, Listing Page (single listing) Translations, but it’s not displaying on the page itself on the front end. When I am looking at it it stays Details. Is there a file with the code in it I can go to and change it there, because this part is obviously not working! Nobody is gonna click on Details when they are already looking at the details (description) of the advert. Thanx a lot.