Yellow highlighted words

I am completely confused as to the function of the yellow highlighted words when bringing a new item in from the Library. I can’t seem to figure out why they are or are not highlighted. I thought these were words that had already been LingQ’d but this doesn’t seem to be the case.

Can some point me to a description of the function of the yellow highlighting? Or, 'splain it to me. Thanks!

If you open a new item for the first time and find that some words are highlighted, it really should mean that you have already saved it (but not yet learned it). Open the vocabulary section and search for the word and I’m quite sure that you will find it somewhere. By the way, if you sort by “Creation date” it may be easier to figure out when you have saved it.