The second picture means striking the string, that is, first dial the four-string empty string, and then hold down the four-string two-pin immediately.

In the third picture, do you mean the 6 in the upper left corner of 7, which is called reclining? Let's take a look at the specific concept.

I'm not sure about the fourth picture, maybe it's to tell you to return to the first position immediately after playing this sound.