I'm not an expert in Magic but i cant figure out how to change the hotbar_count parameter for the default "master" or "wizard" class.

It is set to 3 right now I'd like it to be 2 for that path level. I would also be good with setting it per player with commands. it seems to be in there for /wand configure hotbar_count but it doesn't work. Any help would be appreciated. Have tried changing it in the yml files and adding a master.yml file from defaults and adding in a line just
Master:
hotbar_count: 2

Thank You for the help!