Arrows and Hightlights

I've been watching some of ChessNetwork and Jrobichess's videos, and I noticed that they use arrows and highlights to show possible lines and to show viewers exactly what they mean, especially for people like me, who arent exactly the greatest algebraic notation wizards in the world. :) Anyway, I was wondering if anyone knew how they were putting on these lines and highlights? Thanks!

jrobi has an account on here... Maybe you can ask him. : )

ADK

I was thinking it might be some sort of GUI meant specifically for chess, but it could also be something else.

Coincidentally, I asked him the same thing a few days ago. He says that he uses the aquarium GUI which I suppose apparently lets him set up his diagrams pre-production.