I am sure this is old news to many, but since even a long time user as I only recently discovered it, I figured others might be in the same boat.
When Logos 6 (or whichever version actually introduced this feature) came out and I saw the "Explain the Screen" link (when you click on the question mark/help icon), I assumed that the idea was to provide contextualized help. Instead, one gets a rather useless description of the logos desktop. I incorrectly concluded that contextualized help was not available and manually searched the manual ever since.
However, F1 invoked from a specific type of window does invoke contextualized help. If you are in notes, the help file will open on note documents. If in a passage guide, it will go to "working with guides".
I thought I'd mention it for those who had not noticed.