In the past, I used to sort out all the unknown words before moving on. This means finding their meanings and creating LingQs in necessary.
Now I find it very time consuming. I wonder if I should leaving them alone (as blue), or should I mark them all as ‘Known’? I don’t really know the meanings of those words, but they don’t affect me understanding the context.
As Vera says, it is up to you how you use LingQ. We recommend that you do LingQ all the words you don’t know or unsure of. If you think you know a word then leave it blue. Then, after you have finished creating LingQs, and click the LingQ’d button, all remaining blue words become Known. If you add the odd word to Known that you don’t know it’s not a big deal. Also, if you later decide you don’t know one of these words, you can always highlight it and LingQ it later. If you have a lot of blue words to LingQ, it is a little time consuming but, in fact, if you spend that time with the words, it helps to learn them more quickly.