This might seem like an odd question, but, have you checked Carbonites options to make sure the Quest Watch is not hidden? Since 5.1.2 is the live release version the options are still accessed by: type "/carb options" in chat, right click the Carbonite minimap button and choose "Options" in the menu, right click a non-icon area of any Carbonite map and choose "Options" in the menu.
(Sorry, but the only reason I could figure that you posted a picture of WoW's option panel was because you thought Carbonites options had been moved there in the live release version. They haven't been moved there for the live release version yet.
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