Regarding this instruction:
Keep cache - With the "Keep Cache Between Sessions" config setting enabled, Open a copy of the world in single player and move around to capture all the structures you want in the cache.

Can you explain how to change this setting? Googling "Keep Cache Between Sessions" just shows results from this repo. Is it referring to a line in some json file?

Edit: Answered my own question. It's a setting in .minecraft\config\BBOutlineReloaded.cfg